I disagree. An arcade board has random high speed access to every piece of the program. Something running on a CDROM2 has to fit everything on screen into a pathetically small amount of RAM.
I'm not sticking up for Fighting Street (it isn't very good, arcade, PCE, whatever) but your complaint seems a bit off to me. Are there even any other CDROM2 (not Super) one-on-one fighters to compare Fighting Street to? It would be unacceptable if, say, the music was bad, but I think that maybe Capcom's crappy PCE port of Fighting Street was crappy for the same reasons their crappy port of Marvel Super Heroes versus Street Fighter on Playstation was crappy; no damn memory.
I assumed that the crappy sounding voices were due to the arcade hardware, but I have no idea what the board could've managed in more capable hands (though ample ram doesn't help if the sound chip sucks hard). I'll happily concede the point anyway, since it doesn't change the fact that the Turbo version could've had better voices. There's many CD-ROM
2 titles with clearly voiced cut scenes, and nearly all of Fighting Street's voices are found between rounds, so I don't see why it'd be important to compare it specifically to other CD-ROM
2 fighting games. The static cut scenes in Fighting Street are surely not memory pigs, and if I'm not mistaken, the voices use ADPCM which is separate from the system memory anyway.