I think Apple has a lot of 'help' in the way things don't seem to get fully integrated. If I recall correctly, Jobs mentioned something about working on carriers to carry FaceTime via 3g.
The Mac to iPhone4 implementation is still in beta and works effectively. I suspect we'll eventually see a PC version.
And since the relatively new iPods have FaceTime and the rumors of the new iPads include cameras, I would assume that FaceTime will get more robust with time.
Oh I agree, it's not all Apple's fault. But at the end of the day it's their "revolutionary" product which ends up being just another gadget not many use. Facetime is one of those things which was just screaming to be in Apple's "It just works" hierarchy. You could get a 9 year old or a 90 year old to figure out how to make a phone call in seconds, but unless you are inside wifi and calling another iphone4 phone they will never figure out how to video chat.
If Apple wanted facetime to be ubiquitous they would have considered building a platform for all OSes, including all Mobile OS ie: Windows mobile, Android, palm, meego, etc etc., maybe they wouldn't get support across the board but they could at least make an app and distribute it to those app stores for example.
Sure it's still early, but there are a lot of apps which are catching on that do the same thing. I think its Qik, not sure if that's the right spelling, that Sprint included on my friends EVO. After being frustrated I couldnt video chat with him I found out I could download the Qik app for my iphone, and voila I was video chatting with him over 3g no less, why did I have to hurdle this obstacle in order to video call my friend?