I think I know why I don't like pre evolutions. (and just some cute pokemon in general)
1. They seem like filler to me.
Think about it: They have lower stats, and don't add anything to the game. I think the only reason for adding these pokemon in gen 2 was to showcase and force people to use the new breeding feature.
2. Real Life Counterparts:
This might be just me, but I think if a pokemon resembles a real-life creature, then it appeals to me. The marill line for example:
Azumarill looks like a rabbit, so it is cute in my opinion.
Marill looks like a mouse, so it is cute in my opinion
Azurill looks like... What the heck?
(although azurill is one of the cuter pre-evo's in my opinion.)
Same thing with the pikachu line. they all resemble electric mice.
Since rabbits and mice are cute in real life, when I see a blue rabbit, it's not that different, and I can relate.
But we get to the clefairy line... it's a "fairy pokemon" ok, but what does a fairy look like?
Since I have nothing to relate to, It doesn't seem as cute.
and that's the case with most pre-evo's. they just don't look like their evolutions, or like anything at all.
3. Some of them are just ugly/creepy
Smoochum is creepy. enough said.
igglybuff, well that thing on its head creeps me out, and I just find it ugly in general.
Elekid is... not that bad. it resembles a plug, which is good, but I find it more cool than cute.
Magby: It's pose is sorta weird, especially in earlier games, where they didn't move at all.
Bonsly: I find it cute. it looks like its evolution, it has decent stats, and it looks all happy :D
Munchlax: of course! it looks like its evolution, it has good stats, and well, who doesn't like something that does nothing but eat and sleep? XD
That doesn't mean Ihate all pre-evolutions. I like Munchlax, elekid, azurill, and tyrouge. (and togepi, but that's not really a pre-evo)
speaking of My first reason: tyrouge is one of the few that don't fit ointo this category, because now you can get all 3 evlutions, and if tyrouge wasn't invented, and you could only get 1 hitmon in a game, you would have to trade.
(wait, I'm going off topic! this is supposed to be about cuteness!)
But anyway, everyone asks me why I hate them, and I thought this would be a good place to say it. it's an opinion,
ok people? I just don't find small pink things with eggs that are way too big for them to be cute.
Also, I've been thinking about pokemon with the least cute ones, and I got to... I think steel. only has 3 cute ones: klefki, mawile, and jirachi.