Anyone know why Battletoads hasn't been re-implemented in MAME?

I'm wondering why this game still isn't compatible with the latest versions of MAME. I also couldn't find the reason why it became incompatible. If anyone has the answer to these two questions it'd be appreciated.

 

You can't emulate perfection.

 

Battletoads works in version 0.172 of MAME. It does require some sort of BIOS ROM named bsmt2000.bin which it did not require in previous versions.

 

bsmt2000.bin contains the code extracted from the CPU that runs the sound system and by using it, the sound system can be emulated rather than being faked like it used to be.