The answer to this question is the same when people ask similar odd questions about the 32X, and the answers so far have also once again forgotten the problem. The Sega CD and 32X were both imprisoned by Genesis hardware. There's only so much you can add that can get around the limitation of the stock hardware, Sega learned this with the genesis as Nintendo did for the NES, granted in Nintendo's case they didn't have to worry about the competition catching up.
This is also why FMV is notoriously bad on the Sega CD and one of the reasons why some people dislike those games because they never played good or proper versions of several of those FMV ports unless they had a 3DO, and PSX copies of some of those games, or played at an arcade or PC. You were getting much worse than what was at that time the standard VCR you could get for cheap at a local video store by a wide margin and not just in video quality but color display, with heavy artifacting.
Scaling was in the Sega CD but look at how some of the Genesis or Sega CD scaling ports turned out. Tons of missing objects because it can't draw in enough sprites at the right speed. A lot of detail missing so most ground or wall tiles are just flat single-colors rectangles that move scale-in fast to create the illusion of speed where several of the arcade games had that covered up with something else.
Look at the port of Power Drift on the PC Engine, the Sega CD might do that slightly better but with the weaknesses of the Mega Drive you wouldn't see a substantial boost other than the speed of the sprite scaling itself, for whatever sprites could be scaled since they would be a limit to how many sprites you could use. Same with rotation, Sega CD adds the capability but it's still limited and you have to cut frames when doing so.
if you could get Mortal Kombat CD on there, then why not Super Street fighter 2....3DO managed to get it so why not Sega...and as add-ons go it was quite-successful ...certainly compared to the mushroom that imploded Sega- a.k.a the 32x
This is like saying why not port Virtua Racing on the Sega CD because BC racers is on there. The 3DO is significantly more powerful than the Sega Genesis, CD, and 32X combined. Not to mention that 3Do didn't get Super Street Fighter II, it got Super Street Fighter 2 Turbo which was a whole other animal. I do beleive however the Sega CD could handle a decent though not perfect port of the original Super Street Fighter 2, likely a bit better than the SNES version.
As for the 32X, the add-on was only a failure in that Sega killed it early. It was selling 3x faster than the Sega CD. If anything they should have killed the Sega CD when the 32X came out and focused all those CD resources on the 32X instead. It could have easily sold a couple million or more end of life.
No wonder Nintendo skipped the SNES CD aka PlayStation.
That deal was already falling apart before it was clear the Sega CD wasn't going anywhere.
Doesn't the Sega 32X have a really good soundchip that was completely unused?
Then again looking at the complete Mega-drive, there's a lot of processors to utilize:
The 68000 and the z80 in the Megadrive along with the VDP and sound,
The 68000 in the MegaCD with its own VDP,
And the dual SH2's in the 32X, plus it's VDP and soundchip.
It was probably too much processors for the developers to juggle around.
Quite a few 32X games use it, VF, Cosmic Carnage and others.
Metal Slug was a game with basically no scaling or rotation effects and looked to use tons on animation and so CD systems with limited RAM would have issues.
Some people here will fight you tooth and nail for this fact even with evidence from experience. There were several systems more capable in 2D but they'll argue that RAM advantage having more sprite animations somehow overshadows rotation and scaling effects, or any other Sprite tricks
Sega cd was like the PC engine cd.
NEC relied on the PC Engine CD to stay in the market and actually enhanced games with the CD. There wasn't that much FMV on it outside cutscenes which is no different than PSX games. They even released 2 other variations of it to push for better improvements the exact opposite with Sega's strategy with it.