I thought the day would never come when I would have to make an utterly gigantic post in a gaming forum but it seems that the thread more than demands it.
For starters, I will address your post point by point.
Yes, I know. Every dude knows. Many of the guys who were behind the 'internet culture' are actually boys/men. There has always been sexism/hostility towards the feminine populace and that's not just in the internet. If we are to take any examples... save for the contemporary era in some developed countries, many women are still fighting to earn rights. Internet is somewhat like that for now and someday a change will occur, but women have to be willing to take a crude stance and fight it out.
The dilemma is not just about Riot Games or anything. It's about the targeted demographics. Let's put it this way: The vocal members of the internet community/culture are mostly men. I'm saying vocal, not "the totality". When women will let their voice be heard, things will change. For now, though, they need to form a cohesive unit (just like these mysoginistic fellows you could meet in gaming communities do) to be able to create a balance. Don't expect the voice of one woman to be heard in front of the united voice of over 9000 guys. Do notice, though, that some of us are too damn sweet.
Do note, also, that while some women are not fond of some sexualization, some others... are. I personally know a woman who finds some of the portrayed women rather alluring - though some she found were downright degrading. Likewise, men would find that Gragas is utterly degrading (or a laughing stock) while, say, Malzahar seems to be sorta sexualized - if not for the fact that he's all business. Then again, say, what entices a woman to flip the "on" switch? I'm not sure eye-candy is really the answer, but feel free to correct me if it is.
I will agree, though, on the fact that League desperately needs a bunch of clothed women in the place.
A vocal lady is a start! You gotta rile other ladies up. I'll be blunt here (I'm actually a feminist by nature but I won't hide the sun in a sieve) and I want you to answer to the question I will ask you without feeling hurt:
What is the targeted demographics of this game? [Hint: It's the gaming community in the Internet. Given how men are the most vocal ones in the Internet, I'll let you make deductions.]
Now is the time to raise hell. Rile all the women around you, just go "What SHOULD the targeted demographics of this game be?". Be vocal to Riot games as a cohesive unit, ladies, and I'm pretty sure Riot will gladly oblige in making non-sexualized skins for their female champions, on top of eye candy for the ladies.
Now comes the point, though, when I will do a counter-argumentation. It will be blunt, it will be hurtful probably... but it is meant as a different view of things.
1) I am pretty sure that Riot Games has made content that goes opposite to oversexualizing their lady champions.
- Silverfang Akali looks more like a badass ninja who's out to gut you. I mean, look at that intense look on her face!
- I would say Sherwood Ashe. Focus goes primarly on her facial expression and posture.
- Queen Ashe. Enough said.
- Arctic Warfare Caitlyn looks like a hunter.
- Diana's default skin. She's mostly business. I don't care if her Valkyrie skin changes her outlook, she still stays mostly business. She has a strong personality.
- Nightblade, Infiltrator and Aviator Irelia. Her default skin does let some skin show up, though.
- Karma and all of her skins.
- Kayle and all of her skins.
- Leona and her skins (exception made of Valkyrie). The high heels are not functional, I admit, but it's obvious that her sexuality is NOT the focal point.
- Lux's old splash art (and ingame skin) + Spellthief Lux.
- Morgana is too thin to be attractive in my opinion. Anorexic ladies never had much success with gentlemen. Though, I will admit that her blackthorn skin looks... rather enticing.
- Riven (exception made of Battle Bunny Riven - and hey, I'll come back to it later
- Divine Soraka.
- Vayne (+ Vindicator and Aristocrat skins)
Sure, they could do more but it's a decent start already.
2) Saying that men look for how enticing a female character is to motivate picking them is downgrading men to animals. You somewhat fell into that trap and we feel very, very offended. I know we men are weird but when playing games we're far more preoccupied about the functionality of the character RATHER THAN their looks.
If I were obsessed by looks, I'd be personally picking Mid AP Janna all the time regardless of being countered. However, I happen to not be fond of Janna (yes, I find her looks to be exagerately nude and that somewhat disturbs me).
3) Sometimes, we like to mess with things for the heck of it.
Battle Bunny Riven (also known as Bunnygirl Riven) was an idea by Shaella (who I suspect is a girl) and the community embraced it for how funny
it was. Not for how overly sexualizing it was. I personally embraced the concept because seeing Riven in a bunny outfit hopping around with a carrot sword was like... having a peak at Lulu's mind. As in, it is completely random. Fantastically humorous.
4) These characters are virtual. However, different things stand out for different characters.
Diana's story appealed to lots of people and despite her not being overly sexualized she's been extremely popular. Soraka's old lore appealed to a lot of people, me included. Akali is a hot ninja chick who will kill you (aka don't mess with her). There are many ways to connect with a persona that are not limited to how they look.
5) What appeals to some people doesn't appeal to others.
I know a girl who calls Nocturne and Skarner her "babies" (while for many women out there, Teemo is their plushie). Personally, I find Karthus to be a total badass. Nikasaur (a Rioter) is known for being fond of her absolutely cute Kog'maw. Then again, many League players **** bricks when Rammus (because... ok), Mordekaiser (HUEHUEHUEHUEHUEHUE), Gangplank (eat an orange, be k), Hecarim (My Little Pony~) and Mundo (MUNDO!) are involved (also, yes, these are examples). Targeted demographics play a huge role and Riot has made a huge effort to find something that fits a category.
6) This point has no summary, I'm afraid, but let's try to put an example instead.
If anything, I said that if Blackthorn Morgana was for real my jaws would drop. Then again, she's not real and it's just fine. Just like Varus for you... I mean, imagine if Varus ditched his bow and arrow just to deliver breakfast to you a moment after you wake up... Wouldn't you just swoon? (and yet, we both know that you wouldn't - you'd feel utterly weirded out by such a display). I think you get my point :3
7) Don't forget that some of the gamers are frustrated gentlemen
Okay, I'm gonna get downvoted to hell if I don't remind them of that hot yet unapproachable girl in high-school/college/at work that they never dared to approach or who rejected their advances and stuff blahdablah overly cliche stuff. The problem is, they're en masse >.<
8) You might think that being a woman gamer is important. The truth is, we'll act towards you in either of these ways:
a- omg woman pokemon <3! (the heart doesn't mean we're creepy... just that we <3 pokemons - and that we all are pokemons anyway)
b- go make me sammich (by the way, we don't seriously mean it, it's a huuuuuuuuuuuuuge joke)
c- oh lord, she's trying to make a big deal out of being a giiiirl gamer. We're GAMERS GODDAMNIT! NOTHING SPECIAL!
Well, of course, C is expressed in such an awkward way that it looks downright mysoginistic. B is mostly meant as a joke (and only true a$$holes would seriously mean it - or immatures, let them grow up).
d- OMG WOMAN GAMER I WANNA GET LAID WITH HER; okay, now is the time to just ignore this creeper. Fshhhhhhhhhhhhh-
All in all, I hope you understand my point even though I went everywhere and nowhere at once.
It's partly about making the se.x disparity nil, sure... But it's also about having fun and just ditching whatever sexual references aside and having a good time playing a game.
However... I really want to see a bundle of skins/champions aimed for the ladies... gotta get some eye candy anyway eh? I mean, that Blackthorn Morgana art... (synonymous to 'that Varus art...' for you)