The game keeps making new characters so why not give slots as rewards?
Hero points are already given as rewards. Think of them as half a slot (or 1/10 of slot, or whatever your next slot costs).
I spend most of my hero points trying to get comics just to level my guys since their comic selections are so poor
Hero slots are unfair rewards as they cost different ammounts for different some it might be worth 50hp and some 400 its not a fair prize to give out.
It might be an interesting idea to hand them out randomly, albeit rarely, as part of the daily resupply. Probably won’t happen since there’s already a chance at getting 50 HP but food for thought. I also notice that they have been coming out with a lot of new heroes recently.