What do you expect. AT&T have thrown ALL their weight behind the iPhone for years. Even their current ads indicate as much. "Where are my apps?" "Most popular smartphone(s)". Lets face it, were it not for the iPhone, AT&T would be dead in the water, and in all likelihood, Google, HTC, and AT&T are well aware of this fact. AT&T won't take the risk of backing Android, so they aren't willing to bring enough money to the table to outbid the others for the good Android phones. It's too risky, and sets up Verizon to run ads about having the most popular Android phone or some such thing. Substantial Android backing for AT&T is likely a bad business move FOR THEM RIGHT NOW. Note the "for them right now" statement there please. If at any point the iPhone does go to another carrier, watch them scramble for Android. Until then, don't expect a whole lot of Android lovin'.
Just my two cents. Now, I realize there is one flaw in my logic. T-Mo isn't exactly the beefiest carrier out there. At least, that's how it appears to me (I live in East TN. VZW, AT&T, and US Cellular, in that order, pretty well dominate the market here. Sprint and others don't get a lot of business here). Despite this, T-Mo is getting kick-ass Androids left and right. I, quite frankly, am confused as hell by this. Are they just breaking their entire budget on Google?
EDIT: AT&T will also adopt Android if/when it becomes massively popular and not until. They seem to take a style-over-substance approach. Seriously, last I went in to an AT&T store, they still sold the Razr V3m. It was the most popular phone until the iPhone, and clearly not for function. Style is AT&T's passport to disregard poor service and crappy phones, and people fall for it hook, line, and sinker.