the problem when other emulators use hacks to 'improve' games (and turn them on by default) is that we get a steady stream of people claiming the MAME emulation is wrong, citing the other emulators and 'better experience' as evidence.
it happens with SNES etc. too, there are a ridiculous number of people who think Bsnes / Higgan is a terrible emulator (when infact it's by far the best snes emulator) because it won't run hacks that only worked for other people because they rely on zsnes's buggy and inaccurate snes emulation.