It is a known issue that most human women in League have the exact same face and body: young, thin and conventionally attractive. Why is this a problem? Well, it's been said before: it's boring and a huge waste of creative potential. For goodness' sake, there is not single woman who is obese or has even a single wrinkle! Katarina and Garen are supposed to be about the same age, yet in cinematics Garen has an incredibly detailed face texture while Katarina looks like a literal plastic doll. Even the only elderly woman, Camille, only comes off as old due to her angular face and white hair. (Personal gripe: why say that her hextech heart is the reason for her youthful appearance? "Her face has been replaced with damage-resistant ceramic plates" seems more approppriate for a cyborg.)
Illaoi and Taliyah are great exeptions to this habit, and they show Riot can do better. But since everyone since then has just come from the same old mold, they just seem like token attempts to stave off criticisim. Kai'sa is an infamous example for how the need to keep a character attractive directly conflicts with the story her design is supposed to convey. Sylas at least has some signs of wear in his splash art, like shadowed, sunken eyes, and still doesn't have skintight pants molded around his buttocks. The bigger a weapon is, the more ridiculous it looks when its user is a petite lady. Senna, I'm looking at you. From the champion insights it seems that Riot didn't even consider trying out how different bodytypes would look like. Perhaps Senna originating from an older cinematic limited their design space, but I fail to see why this particular bit of inconsistency would be where Riot draws the line.
"But sex sells hurr!" Zed, Yasuo, Urgot and Gragas have been very popular during League's history, yet none of them are sexualized nor share the same body and face. It's almost like there are more demographics than just horny tweens. Furthermore, most people probably have more than one exact specific appearance they find hot, so you're not even servicing that group well.
"But shirtless men!" I am not here to talk about differences in male/female sezualization in particular, nor if the comparison shirtless dude=sultry pose in lingerie is even approppriate, despite them being related to the issue. The point is, the men in league are still allowed to be young and old, slim, ripped or swole, but the women are not even allowed that. They are young and slim and pretty by default.
"Characters need to be slim so we know they're squishy." Squishiness can be shown by other means than just one body. Jhin is lanky and tall, TF has a mad V-shape with a tiny comic-book waist, yet neither looks tanky. Would you look at a chubby matron in dirty civilian clothing and immediately think "this madam is immune to buĺlets"? This point also falls apart when you look at the champions that are supposed to be tanky, yet still are skinny babes like Leona and Vi.
The worst offenders in terms of unimaginative designs are still the older champions. When Riot comes around to visually updating older designs at some point in the future, I hope they take the opportunity to explore new territories. Why can't Katarina have small signs of aging and a proper leather armor? Why couldn't Soraka have been a middle-aged, motherly figure? Why can't Shyvana look subtly monstrous in her proportions? Why can't Senna have the heft to make her cannon not look like it's made out of carboard? I haven't been exited for new champions' designs for a long time, since they so often come across as huge missed opportunities in terms of creativity. If I want pr0n and sexy, the internet has me covered already. But there are no games I know of where I can play as a hideous, battle-scarred grandma.
EDIT: I ment to write "why cant shyvana be subtly monstrous" instead of Sejuani. Shyvana is a part dragon abomination, after all. Mixed up the names.