Muk is shit. Literally shit. A pile of excrement. Jigglypuff was supposed to be a cotton candy? It a cotton ball or something. Dewgong? It's a normal ass seal. Geodude is a rock. A graveler grows two arms just to lose them when he evolves. Don't even get me started on sunkern and sunflora.
Compare clamperl to shelder. Now walrien to dewgong. Or the Tanoflame series to the pidgey series.
Pokemon fifteen years ago was more simple and generally based off of animals. But every generation has their sour eggs. Sure ice cream and trash are pretty bad but compared to feces? Compared to a rock? Look at it from an 8 year olds perspective, where inanimate objects being Pokemon is just as legit as suped up animals, kids will think the rotom is probably more cool than the ratattata.
Now don't get be wrong. Muk is my fifth favorite Pokemon and Raticate carried me through third gen. But to say that these are objectively better is silly
Edit: just reread your post and realized you probably weren't being the first gen elitest I thought you were being. Yeah design has changed but mostly to just be more flashy