MAME's done, anyone working on it now is just riding on the coattails of the past, IMO.
There's plenty of other new hotness emulators that do a lot more and do the same things better.
and most of them depend on MAME for their information..
You highlighted FBA earlier, but really their devs have never reverse engineered anything significant, they've just taken the MAME code, reworked it a bit, and put it in their framework. They only really touch hardware using common CPUs and architectures etc. too, which is why they've never done anything like Mortal Kombat, or insane multi-cpu systems such as Hard Drivin', because they simply wouldn't fit their framework.
The SuperModel stuff you see, a fair amount has come about due to what progress was in MAME (and MAME keeping an organized record of the correct ROMs etc.), even if their end project was a lot better. The original SuperModel findings were put in MAME years ago, and remained there until they were needed again recently (the original SM devs were MameDevs)
ElSemi (with his Model 2 emu) was probably the last dev outside of MameDev actually pushing arcade emulation at all, actually discovering new things, and implementing them in a polished, working emulator. Some people are apparently having issues with his no longer developed emulator on more modern 64-bit platforms etc. tho.
Keeping MAME alive and active is important, because even if you're not benefiting directly from it, you're probably benefiting indirectly from people using the information contained within it, which was kinda the point of the project anyway.