>>32744042They're all ugly as sin, and the people they're designed to pander to (i.e. nostalgiafags) didn't want them.
Megas tore a hole in the meta game when they were introduced, and are almost solely responsible for the power creep we've seen lately. Gen 6 introduced more 600+ BST monsters than every previous generation combined. And gave them all broken ass abilities.
There is literally no reason for megas to exist. Mons that should have gotten normal cross gen evolutions like Sableye and Mawile will never get them now. Since you're only allowed one mega per team, people pass up lesser megas that they might have run if they were normal evolutions (see pretty much every mega in a BL tier).
Literally the only advantage megas have over normal cross gen evos is that they can be used to buff 3rd stage mons. Except this could be accomplished by simply restatting the mon and giving it new abilities (GF has shown they're willing to do both). Even then, GF fucked that up by giving megas to mons that were already really good (Scizor, Garchomp, etc.), so any future megas will face stiff competition for that mega slot. That is, if GF ever makes new megas.
The worst part of megas is yet to come however. Gen 6 set a precedent with these stupid LIMITU BUREAKU mechanics Japan is obsessed with. As Gen 7 showed us, GF wants to chuck out new gimmick forms instead of trying to properly balance the shit they've already made. In a few gens, the game will be so bloated will alt forms and transformations, it'll be an unplayable mess.