In a world of unlimited bandwidth, I would agree with you. But it's not, so I don't.
As we should have all learned by now, AT&T probably doesn't have the network capacity to deal with this kind of heavy use. Other cellular providers may find themselves in a similar predicament if suddenly faced with 250MB/hour streams.
Self-imposed throttling of bandwidth usage on a low-bandwidth network is simply being a good network citizen. This isn't Apple exerting excessive control, because bandwidth limiting is needed. To give a potential real-world scenario, I don't want to be blocked from internet access because the stadium next door has a few hundred fans trying to simultaneously stream the ballgame to their devices (whatever those devices may be).