>> it is. but you use very outdated source code and so you can't know it.
That's great, really is. Can't see how it was done exactly, but I clap my paws to no more #IFDEFs. Who did that?
I actually refer to more than dozen MAME builds from 0.34 to 0.141, as that was the latest when I started my re-writes, I guess these changes happened in 0.142. What a day!
So, as I gather the reason to have combined build is just about MESS developers wanting to step a little bit under the spotlight. No any practical benefit for either developers or users, except hope this might bring a few more testers. I think who cares already knows about MESS, but people will not use MESS instead of SNES unless it is actually better. MESS in MAME or its accuracy will not bring new users, only speed, compatibility and simplicity might, with or without MAME just the same.
However, most of the simplicity points you loose just by being multiple instead of single console emulator, unlike MAME. It's because when people are interested in arcade games they are interested in all or most of them, but with consoles everyone has only one or few they care about, so all the rest of the stuff is more like "cancer" rather than just an "option". The rest of what is left of those simplicity points you will lose by merging it with MAME, and even if you somehow make it more simple than it was before there is still no any particular reason why someone who want's to play SNES would download 100mb binary with all sorts of crap that is of no interest to them and spend days on configuration when they could play SNES in matter of minutes.