In terms of Akechi, you do have a point. I've discussed why him being revived would piss me off before, so I won't get into it here. If dead characters do show up, I'd like it to be in non-canon ways, so as to not drag down the plot of the mainline games. Like, if he were to show up in the inevitable P5 Arena, have him be the public's cognitive version of him or something. It's not actually Akechi, but he's still in the game. Or even better, have him do nothing in the story and only have pre-match dialogue and win quotes.
Christ, I got off-topic there.