The turn button was one of the reasons I hated MKM. If they were to do something like this, they'd have to ditch that and just go full on arcade beat em up, Streets of Rage style.

The stance change is a good feature, thus not pointless.

If my idea was used, then these segments shouldn't just involve fighting, they could also involve avoiding or destroying obstacles, finding important items, etc.

Character chapters could really just be MKM:S-like levels featuring a certain character, sometimes teaming up up with others. When that happens, you can switch characters, with the other(s) serving as AI-controlled assistance. If one of your characters dies, he/she can no longer be used. Character deaths in "co-op" levels could affect the outcome of the story, they could force the players to play as a different character in other levels, they could even make certain levels inaccessible.

Once you've beaten the story mode on the hardest difficulty setting, you have the option to play as anyone you want in any levels. You could use Kai in a Stryker level, for example. When playing as an unintended character (so to speak), you get no cutscenes, just the gameplay segments. Although I wouldn't mind non-canon cutscenes to justify (even if unnecessary) what Kira is doing fighting an enemy of Shinnok she has absolutely no connection to.