I can see where you’re coming from regarding OMK but it’s not really like that.
For a picture of OMK upon release (the only time it had a chance to get a following), it was designed more in a traditional paradigm of no airblock, usually no airdashes, etc., but it made some odd choices. Basically 70% of the cast had no anti-air at all, including the “grappler” character, so there was essentially no grappler character (instant regular throws hurt almost as much anyway.) Instead they relied on air-to-air, so you spent enough time jumping that the neutral game resembled a strange, slow imitation of vampire savior (plus similar running dashes, I guess.)
You could draw some comparisons to “random poke into chain combo” but it wasn’t even like that in OMK, because few characters actually had pokes worth anything. You’d normally have to be lucky enough to have a chainable poke and some kind of slide normal to get you close enough to continue, and footsies were still very limited. Plus, the timing on chains was quite strict (patched later), so you had very little freedom in this area.
I think those are the main reasons for claimed lack of character variety in that game.
In SFxT there is the danger of good pokes leading into long hitconfirms, but that isn’t really something from OMK. If you’re worried about combos being same-ish, I honestly don’t think that most characters will be doing LMH LMH for too long. People will attempt to drop their lighter hits for scaling, at least.
Unlike OMK, where any other type of combo was limited to a single juggle hit, the framework at least exists for different kinds of juggles. You don’t need to tag to continue your combo (ground bounce, wall bounce exist), and I’ve seen some other examples in videos of different frameworks for combos (for example tag into jumping chain, land, continue with ground juggle, or ibuki’s stand roundhouse xx command dash looping a couple times.)
I’m not speaking here of any kind of judgment on the game itself, but I don’t think the comparison to other games really holds up past the superficial stage.