>>58594805
Megas are temporary powered up forms filled with life energy, it's not a full blown redesign.
Although now that you spoke of it, it really does feel like Gamefreak does try to push some Megas as redesigns, they fucking hate Feraligatr and made it's Mega a dogshit humiliation ritual design and Baxcalibur on the other end of the spectrum finally feels like it's design was finalized and this is what regular Baxcalibur should look like.