My thoughts are not random but are in fact direct responses to your random thoughts. Read on:
1. What LIRR diesels are you referring to? If you mean their freight-type locomotives, it's because those were common engines that already exist in model form or are easy to kitbash. And I think it's already been established that commuter models are a limited market, so that should pretty much answer your question right there. Incidentally, though, Funaro & Camerlengo does offer some resin kits for older LIRR coaches.
2. I don't foresee an injection-molded kit for NEC high-level platforms like Walthers did with their Union Station platforms. Why? It's a limited-interest area (how many people have actual contemporary NEC layouts?), and high-level platforms are tricker to install on a layout because we rarely have long enough sections of perfectly straight track. It would be better to build your own platforms from styrene or wood so that you could custom-fit them to the curves of your trackwork. And would it be so hard to scratchbuild something that's basically a large concrete block?
Another thing to remember is that not every station's platforms look the same. I can't really picture a generic "NEC-style high-level platform" because there are so many variations. What you could see is a kit with some platform details, like trash cans and ticket machines, that you would add to the platform you built. But trying to consolidate everything into a mass-produced kit? Not so likely.
3. See above...I could possibly see an add-on kit containing elevators and escalators, but again there's the problem of different styles. A better idea is figuring out exactly what your elevators/escalators need to look like, then building a master and casting your own. For scenic details, it's perfectly okay if you're not turning out pro-quality castings. But hey, you don't have a layout to install platforms on, so why worry so much in the first place?
4. Yeah, that's nothing new to model railroaders everywhere. But a decade from now you'll be glad you bought certain trains when you did, because they won't be available anymore. Or maybe you'll make huge profits selling them on the eBay of the future because they're completely mint in their original boxes, never having been run on a layout.
5. This is something I've seen a lot of people saying lately, and frankly it annoys me that people dismiss themselves so readily. Do you think the rest of us were just born with the natural ability to kitbash, scratchbuild, and airbrush? It takes a lot of TIME and PRACTICE, not to mention money, to develop the skill and craftsmanship needed to turn out high-quality models on your own. I got started in the hobby around age 6, and it wasn't until age 16 that I finally finished my first "good" model. Ten years is a long time, especially for a young person, and it includes a lot of crappy-looking models! In the three years since my breakthrough, I've gained more experience and am
just now working successfully on projects that I've been dreaming about for many years. And believe me, I still have much more to learn! Granted, it's different if you start the hobby at a later age than I did, but the point I'm trying to make is that NOBODY will be a John Allen right from the start (and if you don't know who he is, you got some reading to do). You're almost insulting the rest of us, who also didn't know an X-acto knife from a razor saw at one point long ago. But we didn't give up and resign ourselves to only collecting trains. Think of it as a form of education that you go through...and even once you graduate from the high school of model railroading, there's still college and grad school coming up around the corner.
My advice? Assume that it will take you a few years to learn the basic skills you want, and buy some cheap Athearn models to experiment on. Try kitbashing them together, try painting them yourself, try anything you want to. That way you won't be ruining any expensive models when you make mistakes, and eventually when you become comfortable with modeling, you can start to work on some "real" projects. But it's not going to happen overnight, and I honestly believe that ANYONE can become an experienced model builder with patience and practice. But don't use the excuse that you don't have the skills...if there's anything you lack, it's the determination to stick with it and learn the skills on your own.
(By the way, the NMRA and possibly other organizations often hold clinics for people wanting to learn the basics of the hobby. You see these often at train shows - lots of them deal with scenery, but I've read about clinics that describe the basics of detailing a locomotive. Help is out there if you're willing to take the time to find it.)
6. The Silverliners sold at the SEPTA museum store are basically toys. I would consider them souvenirs for kids who ride the real thing and want a model they can put together themselves. I really don't think they were intended to be scale models by any stretch; after all, it was SEPTA who commissioned OK Engines to produce the models (from my understanding). It's not like Walthers suddenly decided it would be a profitable venture to produce Silverliner models. And hey, SEPTA can charge whatever they want, because obviously some people are willing to buy them.
7. Because for them it's just a job. Of course there are some railroad employees who are also railfans/modelers, but not as many as there used to be. Try to think about it in other ways - this would be like having flight attendants who were fanatical about the airplanes themselves, or garbage collectors who went around taking pictures of garbage trucks in their spare time (no offense if any of them do). We might love trains, but for most other people, trains are just a thing that gets them from point A to point B.
8. Maybe you should start the first one, then. Also, your definition is somewhat broad. What kind of model railroad sites that specialize in commuter railroads would you want to see? Manufacturers, models, layouts, ideas? Remember again that commuter models are not as popular as other types. I'm sure some of the people you see buying the models aren't actually commuter fans, they just need a train for through service on their freight-themed layout. Or maybe they're like you...buying the trains because they love them, even though they have no layout to run them on. (Not that there's anything wrong with that - for all intents and purposes, I don't have a layout either.)
I do know that there are others out there who focus on commuter or other passenger equipment, and I wish more people would either start their own websites or share photos by means of existing sites. But you're not helping the cause by wondering why anyone else isn't doing it - the best way to accomplish something is to take action yourself. It takes a lot of time and effort to run a successful website, so if you want one, there's your plan of action. Start a website that you intend to be the #1 commuter modeling site on the net, and encourage people to submit content in addition to what you post on the site. How else are you going to get what you want, when you want it?
9. I've not heard of anyone working on either of those stations in their modern form, since the nightmare of trackwork in addition to scratchbuilding the platforms and terminals would drive most people nuts. I believe there's one fellow working on a Chicago-area Amtrak/commuter layout, but I've never seen photos. Also, the famed John Pryke models the New Haven in the 1950s, and I'm pretty sure he included South Station (or at least the area around it) on his layout. Photos of it show up from time to time in Model Railroader - there was one a few months ago that I believe showed the throat tracks of the station - and the layout was featured in a Great Model Railroads publication at some point. Search the magazine index at
http://www.trains.com for clues.
Myke, you clearly have a lot on your mind, which is good, but I think you'd be more satisfied if you did more acting on behalf of your thoughts. I believe I've provided you with some ideas to build on, so I suggest you go forth and do some further investigation of your various questions and desires. One of my favorite parts of the hobby is researching, because it's just such a great feeling knowing that I found the information without anyone telling me where to look. And don't forget, the Internet doesn't have every bit of information that's available. Even as recently as a few years ago it was still more helpful to go to a library and read through back issues of MR, RMC, MRG, MM, and any other magazines to learn about the hobby. Just because it doesn't show up within the first page of Google results doesn't mean it doesn't exist anywhere.