A lot of games will let you remove assets you put into something so you can re-distribute them to something else… for a price. Why doesn’t HH allow this in Hero hunters? It might be a decent way for them to make some money, while also allowing players to change heroes that were once decent, but got nerfed one too many times.
Of course this might just lead to even more stagnant PVP with everyone running the same heroes, but I think it would be nice to take fragments out of heroes that are no longer useful. For instance I have Matador at 9 stars right now and I never use him for anything. As soon as I get him to 10* he will be able to collect heronium, but I would almost rather take all the fragments out now and dump them in a useful character.
Maybe they could allow you to get back all your fragments for say 500g? Matador could then be taken out of your roster, or reduced to level 1 or 2 and all the fragments used to get him to the current level could be refunded as mech frags. So for example if I paid 500 gold I would get all the frags I have in my 9* Matador back, which would end up giving me a 2* Matador and roughly 1500 mech frags.
Another option would be rather than paying gold, you take all the frags out but lose say 10%? So in the example above, instead of paying 500g I would pay nothing but only get roughly 1350 mech fragments back. This would deter people from constantly changing heroes around, but still allow them to fix things for a cost.
Of course they could also do a mix of gold and frag reduction.