Whats also big is the exclusion of flash. The reason is obvious. No flash. Far less streaming over 3G. Less streaming over 3G means less bandwidth consumed. Less bandwidth consumed means ATT can offer a GREAT price on the 3G data service. I personally have never had problems with the ATT Network. The limits on 3G streaming probably means I wont going forward either. Thats a good thing.
I don't think that's the reason. The primary provider of streaming Flash video is YouTube, and despite the iPad's lack of Flash, it ships with a built-in YouTube player.