Sticky grenades would be basically identical in function to a launcher, and charges can be supplemented by a launcher as well. I'm strongly of the opinion that grenades would just make explosives more spammable, where I believe they should be used sparingly against fighters and to blast open doors and walls.
Honestly, I do believe a launcher serves all of our explosive needs. The devs can adjust the reload time and ammo availability for the launcher as well to balance the use of explosives by exos. Adding grenades and charges seems like addition for the sake of it, which wouldn't add any new functions (aside from making explosives more rapid to use) and would just increase the number of things the devs have to balance.