TL;DR Have the starter final evolution designs "objectively" gotten worse, or is it a subjective thing? They seemed to be pretty well liked till gen 5 onwards, where things got "controversial."

While obviously whether you dislike or like a design is subjective in it of itself, when like 90% of the fandom agrees a design is bad, it starts to break the "subjectivity" a little bit. Cuz you're pleasing only 10% compared to the other 90%.

Correct me if I'm wrong, but starter final evolutions seemed to be pretty harmless till gen 5, with Samurott who looks nothing like Dewott, Emboar who is a weird bipedal big and Fire/Fighting again, and Serperior who suddenly has no limbs.

Venusaur and Meganium often released some flack, but they weren't really "hated," it was just that people found Charizard and Blastoise for gen 1, and Feraligatr and Typhlosion for gen 2, much cooler. And it's not too difficult to see why, as fire and water designs often look more tough and battle-ready.

Then in gen 3 and gen 4, though Blaziken and Infernape seemed to be the obvious favorites, the others were still liked pretty well. Sceptile and Torterra were the most popular grass starters I think, and Swampert and Empoleon had amazing typings!

In gen 5 though...people seemed to actually HATE the starter final evolutions. And it wasn't too uncommon to box the starter altogether.

Then for gen 6 they were considered pretty underwhelming/disappointing except for Greninja, who somehow got to be almost as popular as Pikachu, Charizard, and Mewtwo.

Then for gen 7, Incineroar was disliked for being bipedal and looking fighting, Primarina was disliked for looking even more feminine than the already feminine Meganium, though Decidueye was pretty harmless, though not nearly as popular as Greninja.

Then for the latest, gen 8, people seemed to hate them almost as much as gen 5, if not more. Rillaboom is kind of liked for ironically looking the least humanoid despite being a monkey, though people agree the drum looks stupid, while people disliked the humanoid bunny Cinderace, and humanoid lizard Inteleon.

The pattern seems to be that gen 5 got a lot of flack, and then the humanoid designs in gen 6 plus were also disliked, while the less humanoid ones like Greninja, Decidueye, and Rillaboom were more well liked.