They didn't do any testing on it. Their logo isn't on it. If someone has a problem with it they can just say, "well if you want to have a seamless experience on our network you should buy your phones from us instead of a third party." They don't support the Nexus One at all. It will be the same thing for the Streak when it's released. It will work on AT&T's bands, but AT&T won't (initially) offer it.
Don't use the stuff they put on the phone if you don't want to. All phone carriers are doing this. And I don't think they are limiting any apps. I also think there will be an uproar if they remove google search from a high end Android device, and AT&T also knows that. The backflip was a learning experience that I doubt they want to experience again.
The theory makes sense, but I am still skeptical about such a thing happening. Also you don't know anything about the Liberty/Aria/Intruder. For all we know, they could be 3 different devices. Or 2. Maybe they want to have a high end and low end HTC Android device launch at the same time. They had that one phone in the video on youtube blurred out. Maybe that was the Intruder, which is rumored to be about the height of a coke can. That is tall enough for a 3.5 inch display. That's nothing to scoff at. Maybe both of them have Snapdragons. We have only seen one Android device from AT&T, and that's not enough to notice a pattern. These next few months will though.
Yeah I am not particularly happy about it either, but it is what it is.
EDIT:Also for the people getting really bent out of shape over this stuff, switch carriers. You won't have to keep waiting and you won't have to deal with AT&T.