Quoted By:
Mega evolutions are a hit and a miss, some of them were much needed but at the same time would have just been better as a normal evolution.
Take Banette, counterpart to Dusclops in Hoenn, both pre evo forms evolve at 37, pure ghosts found in the same place depending on the game and Dusclops got the better end with an actual evolution and gen V it got eviolite meaning both were viable. Banette was complete shit during both those times, and it gets a mega after time, its still pretty bad because Prankster isn't a thing turn one it megas and its forced to use its stone as a held item in order to be good. Hell, several pokemon who have megas don't even need them or use them that much, Alakazam, Heracross, Scizor, Gyarados, Garchomp and so on. Of course that would be too complicated for gamefreak so this gimmick is their best call.