Proactive/reactive makes far more sense than active/passive; I’ll go ahead and use these terms instead :P

It definitely should be possible to differentiate characters in character-based games like Disgaea or Musou, the example of FEW seems promising (and I would play it if I hadn’t completely burned myself out on Musou already). DW8 (the last good one) actually did have a weapon triangle system, but for the reasons you describe it could never be used to actually restrict effective playstyles — instead you would just give every hero two weapons of different types (iirc).

One thing, though, is — even if you differentiate characters and force some level of strategic decision-making, is that contributing to making the map unique? My impression is that even in FEW, the kind of tactical decision-making you have to make with multiple commanders and the like isn’t deep enough to give each battle a unique mechanical flavor in the way that a mainline FE game or an AW game might.

When writing this article I was also thinking about the introduction of special boss mechanics in JRPGs — I almost touched on this with Disgaea’s Baal. I couldn’t really formulate it (will probably need to play a few more JRPGs first) but I feel like they’re rarely very strategically deep — felt this constantly in Persona 5. Haven’t played Setsuna but I’d be interested in a JRPG that actually manages to make an array of tactically interesting boss-unique mechanics.