Why no MMS: because MMS uses a completely different and increasingly out-dated connection system (WAP). It was decided that the n900 would not natively carry more than one apn - and that would be your GPRS/2-3G signal. Persuading n900 to create and connect to a separate apn was a chore in itself (it's no accident that's done with a separate programme before fMMS gets going). These days MMS is about the only thing which WAP is still used for, I think.

Nokia made a conscious decision not to bother, probably in order to focus on other things. When Frals stepped up to the plate they have supported him handsomely in making fMMS as the excellent solution that it is. And it's improving all the time.

If you are having problems with connecting to the wrong apn routinely, there's a fix for that. Try this.