Johnny didn't want to be at war with the Angels Of Death or other gangs, yet he was still able to go on intense gang wars with his battle-hardened crew, blowing up vehicle transport or clearing a whole hangout area for the fun of it. Luis didn't want to be a gangbanger either, he just wanted to work in the club to make good legal money, but he could still go on drug wars with his friends. Seriously, the story shouldn't gimp gameplay. Going on rampages doesn't make sense for Michael or Franklin, but you can still do it. Pretend it's Out Of Character if you don't like it or don't even use it, because more content is always good, because someone else will like it. The sole reason SA was so damn good is that CJ could do everything, now with the multi-protagonist system it would have made even more sense. Hell if you don't like CJ, go get the PC version, get some player mods and or change the voices.
Stop. No. How many people have completed the game? By the end of the game, and from the beginning, Franklin wanted to get out of the gang banging scene which he did. Why would he go back to it if he got out like he did? He's not a part of the Families anymore and wasn't too strong of a member to begin with. So no. This would be catering to the SA fanboys.
OP's ideas are very very good I like the idea of being able to set houses on fire, Anti-Firefighter!
Oh no...someone else using logic again!