Sexualization: What's okay and what's not
Expanding on a Reddit comment I made two weeks ago and a boards comment piggybacking off it.
I've seen a lot of people complaining about "x champ is too sexualized!" especially with Riot's admission about Kai'Sa's neckline. So I'd like to shed a little bit of light on the issue.
As a preface, I'd like to praise Riot for making some amazingly diverse and realistically dressed female characters over the years: Diana, Quinn, Kalista, Rek'Sai (hehe), Illaoi, Taliyah, Camille, Xayah (who's SUPPOSED to look like she just came out of Hot Topic), Zoe (yes even her), and most recently Irelia. (I'm probably missing a few still.)
Here I list a few categories of sexualization (and bad wardrobe choices), and copious examples of each. I hope this analysis clarifies things a bit. And no, I did not forget the guys! They are actually a lot more diverse by default since we have a lot of dude monsters and not a lot of lady monsters, but the body types of just the human men are pretty diverse compared to the women (who have a lot of big boobs and wasp waists and a handful of exceptions of different types). And their outfits/armor are a little more suited to the task. But I'll save my boob plate whining for another post.
Makes Sense
Evelynn: She is literally a succubus who exists to torture and hypothetically have sex with unfortunate victims. No problems with her being nearly nude.
Elise: Literally makes blood sacrifices to preserve her youth. Of course she wants to show it off. No problem.
Ahri: Added by popular demand. I wasn't originally going to add her because in the grand scheme of things her outfit is not even that bad. She is still a seductress, though. Ample cleavage is warranted.
Miss Fortune: This is where it gets a little hairy. Her VO and base skin take her sex appeal over the top, and these both need changes - but it's still canon, and still warranted! Hear me out. We know thanks to all this juicy Bilgewater lore that Miss Fortune is a fucking badass - survived getting shot in the head by Gangplank as a kid, eventually took Gangplank's spot as ruler of Bilgewater by blowing up his ship, capable of blasting shitty people to bits, etc. We also know, thanks to the comic "Fortune Smiles," that she's willing to use her looks to her advantage, by pretending to be a demure lady to trick her rivals into thinking she's weak, before striking back and shooting them down. So yeah - it's completely fine that she's sexy, but I'd really just like to see her get a new voiceover (this has been in the works from what I've heard), and also get the GP treatment: swap base and Captain, new title (the Pirate Queen? Bilgewater's Queen? the Bullet of Bilgewater?), call her old base Bounty Hunter MF, problem solved.
Sona: Some girls are just naturally busty, and it's her choice whether she gets to show it off. Like, I'd PREFER if she didn't look like her dress was about to fall off, but she's fine as is. EDIT: There's a difference between a musician in a long, flowing dress who doesn't actually canonically fight, and an assassin, frontline fighter, or backline marksman who all need some utility in battle.
Taric, Kayn, and Rakan: If they want to show off their abs, then so be it. EDIT: Rakan and Taric are both capable of shielding themselves with magic, making their clothes basically irrelevant. Kayn's in a grey area. Technically he might not have to wear armor, as he's presumably able to evade most attacks with shadow magic.
Doesn't Make Sense (aka Rito Pls Fix Someday)
Kai'Sa: I can understand the clarity stuff, but can that V-neck not go below her boobs? Well, I guess it's too late for that, but you get the point. A Void suit has no reason to avoid her cleavage.
Katarina: Why is an assassin wearing a glorified battle bra? She'd die instantly in the fray! EDIT: To clarify to those dense enough to think this is protective at all, her heart, liver, lungs, guts, etc. etc. etc. are ALL at risk.
Ashe: Why is she wearing thigh highs and a minidress in the freakin' FRELJORD? EDIT: While she may be cold resistant thanks to ice magic, I still imagine her wearing something like this instead https://greyhues.deviantart.com/art/Ranger-455050405
Caitlyn: There's room for fashion, but not really for frilly skirts on a cop. Especially when you're tackling people to the ground. Cait's visuals and VO are horrendously outdated in general so if there's anyone on this little list I want to see updated ASAP, it's her. EDIT: No, she is NOT just a sniper! See: "Progress Day"
Syndra: Just isn't wearing enough. And isn't cohesive with the rest of Ionia. We'll see if whatever lore update she gets justifies her outfit.
Sivir: Also isn't wearing enough, but at least she's not as incredibly sexualized as some of the others on this list. Also she lives in the desert which is technically an excuse. EDIT: Yeah, Egyptians weren't wearing much at all but they were probably wearing a bit more when actually in battle. Sivir technically strikes from the back line, or from far away, but there's still the possibility of getting hit by a bounty target.
Shyvana: Ugh, battle bra. EDIT: What I mean to say is, why is she wearing metal armor at all? You could literally just give her thick scales on her body and it would have the same effect.
Sejuani: Editing Sej in because her armor's certainly better than it used to be, but still not enough. Here's why it sucks. A blade that goes in that boob window is gonna just kill her. A blade that hits the boob plate is going to deflect off and end up right in between the cups, and whatever bit of metal is over her sternum will cave in and stab her in the heart. Kayle has this problem but she's getting VGUd so I won't complain unless she has it afterward.
Leona: Also editing Leona in. She has the same issues as Sejuani but without the skin window. To be fair, though, she has a giant shield to do most of the work.
Grey Area/Whatever
Soraka: EDIT: Soraka is probably fine in the grand scheme of things.
Zyra: She's a plant. She just modeled herself after a woman.
Nami: The "clothes" are a part of her body. The V neck is a questionable design choice, as is the fact that she has boobs to show off at all (it's unlikely that the Marai are actually mammals), but her mostly fishy nature sets her apart from other mermaid concepts which is at least nice.
LeBlanc: We don't know if that getup is all an illusion. We also only suspect that it's her in the cloak as the Faceless, but if that is her, she's due for a very Noxian wardrobe change. (Maybe not a cloak buuuuut...)
Janna: Her outfit was certainly inexcusable when she was a human air mage. She's a spirit now, though. She could use more creativity in her outfit instead. (Also now that she's a spirit she should really drop the prostitute joke. It's a classic for sure, but really?)
Nidalee: Feral woman. Realistically would not be wearing much anyway.
Varus, Aatrox, and Rhaast: They're not even human. They don't give a fuck. EDIT: Remember that their armor is part of their bodies, except for Rhaast wearing Kayn's pants.
Akali, Morgana, and Kayle: Getting VGUd. Will likely be far less sexualized (Akali/Morgana) or wearing armor that isn't going to kill them (Kayle) once complete.
Cassiopeia: Editing Cass in. FURTHER EDIT: Yeah, I get it, she used her looks as a weapon BEFORE she became a frickin' snake monster. I'm not so sure about that now. So... is she still... making use of that battle bra?
Braum: Editing in. IF Braum is human, then yes, the fact that he's shirtless is Not Okay. However, there have been arguments that he's a demigod of some sort (hence cold resistance), or that he isn't even real in the League universe. Status questionable.
runs around shirtless in the frejlord, so does

has a tunic and
wears nothing but a kilt
has boob armor with exposed clevage