It just seems to me that, given the supposed challenge of supporting these phones with multiple updates (Google has to push an update, but first the mfr has to bless it, then VZW has to bless it before it gets pushed) it makes sense to utilize a 3rd party - and there is already an excellent and eager community in place.
Flashing a rom is relatively simple (at least on the D1). If you look at PC's, don't sell everyone short - a lot of people are using freeware programs and just look at how many use Chrome or Firefox. If the masses get pointed in this direction, the financial support will make the roms even better to the point where it will become indistinguishable from simply downloading an app that installs itself. And a lot of the tweaks are being automated and made quite simple, as well.
Of course, the mfrs want people to buy a new phone, and in that regard roms are a threat because it extends the life of the phone beyond even the latest Android update. And then you have the carriers who are worried about revenue streams evaporating when people bypass controls on tethering and the like.
The only factor in this game with any leverage to change that dynamic is Google. Android is free, and vs. other options out there that creates a lot of value for the mfrs.
The only way any of this will change is when the masses figure out some mfrs are terrible at pushing update and choose another phone as a result. For all the attention Samsung is getting, I'm not sure it's really visible in the MSM and so most of the masses aren't going to have any clue.
It's really starting to look like a market that is growing too fast for the mfrs and carriers to keep up with. Apple has been at this for years, and is GINORMOUS. They've had time to put the infrastructure in place to support and clearly the other mfrs and VZW are not there. And who know how much pressure VZW and the mfrs are really even feeling to beef-up that support infrastructure.