I also can't for the life of me imagine why the iPhone config utility doesn't have fields for MMS. It seems like such a strange and pointless omission.
I think that Apple has worked very hard to cast this image of themselves as the champion of the end-user. If that's the case, then they need to start proving it with mobile devices like the iPhone, which occupies a market segment where users have traditionally not been regarded as much more than pawns. I feel as though Apple here is treating this situation like their ongoing business relationship with AT&T and other carriers is more important than satisfying the needs of their customers whenever the two are in conflict. I suspect that Apple wouldn't want that kind of press.