I've been thinking about how Mega Evolutions differ from regular evolutions, and I think a big component of it is that while regular evolutions seem to represent maturation and growth, mega evolutions seem to typically look more like the base Pokemon with additional equipment, like armor or weaponry. It's more like a costume change (or a powerup) than a physiological metamorphosis.

I think it's why a lot of the mega evolutions are so boring design-wise. It's literally just the same Pokemon with a bunch of shit thrown on. With only a few exceptions (such as M-Slowbro), the designs don't simplify any aspects, they just take what's already there and expand upon it.

It's also why a lot of fake mega-pokemon look so unnatural, because they're designed to change the physiology, rather than just "armor up" the existing base. Stuff like the Mega-Klingklang that looks like a train, or the Cofagrigus that comes out of its coffin are too hard of a base form shift to be realistic Mega designs. Which sucks because those designs rock, they're just better suited for traditional evolution.