>>58461130I think my issue with Mega Starmie is that it very clearly isn't a natural progression from Staryu-Starmie, pic related is at least closer to what I would've expected a Mega Starmie to be before we started getting all this shit shown for ZA, admittedly it's leaning a bit towards a reef aesthetic which I think is an incorrect interpretation of Starmie but it does build on the starfish elements at least and I'd want it to also add to the jewel and gold ridges as well. I do like that OP's image incorporates those elements by having the tips of the legs become rubies as well and further developing the gold.
When I think about the Mega Pokemon from XY/ORAS I think most largely fall into being a natural progression of the original Pokemon by making the notable features (which in the case Venusaur, Alakazam, Houndoom, Garchomp, Steelix, Sharpedo, Altaria, Salamence & Metagross were already progressed through the original evolutionary line) develop further or reincorporate elements from a pre-evolution to build on the Pokemon (Gengar, Gyarados, Ampharos, Tyranitar). In the case of single stage Pokemon I think there is a bit more liberty but I think the only ones that betray their original designs were Heracross (just due to how it changed the horn structure) and the Latis (An admittedly very boring Mega evolution pair and definitely a let down for those legendaries).
I think that's what's missing from a lot of these ZA Megas is that follow through, there are still some that work like Meganium, the Kalos Starters, Barbaracle & Dragalge. But a lot of them just go for their own thing and suffer for it. Also for at least a few they feel like they're leaning into something closer to a Gigantamax Form where it's making one element of the Pokemon overly massive (the closest I think in the original line-up for comparison would be Blastoise) even if that design element wasn't particularly significant to the Pokemon originally (Victreebel, Feraligatr & Greninja).