Removing his passive would be disastrous for Junkrat. The part with exploding upon death could be removed without any issues. But making his grenades and ult hurt him like in the old days would absolutely destroy him.
Not only is it a clear nerf because you remove so much potential output, but also the game now has more dive and brawling kind of heroes that it would place him in a even weaker spot than back in the day where he was considered a troll pick.
If other heroes should have a similar passive is a whole other discussion and I dont think that should have anything to do with junkrat individually.