Why would AT&T have a restriction on MMS? They don't have one for any of their other phones. Please show evidence for MMS being a dying tech, if anything it's becoming more popular as more and more phones come with cameras and video capability.
Video is not the only component of MMS, and if Apple was that concerned about battery life, why would there be Maps, games, Cover Flow, 3G, wifi, etc? Actually if they really wanted to conserve battery I'm sure getting rid of the huge screen would be the #1 priority.

The iPhone can't record video so that doesn't matter, and honestly I don't have an issue with it not being able to play videos either - but the basic ability to send/receive photos? I fail to understand how that drains the battery more than anything else the iPhone does.