You are being rather bias tbh...
Riot is not simply marginalizing females. They also can not control how some players treat females but can reduce such toxic behavior through tribunal/mute/etc. To make matters worse many females use their... assets
to garner attention (while this is not exactly wrong in the real world under moderation, doing so in a video game community is just pointless).
Naturally, Riot will make character models that will attract attention and fit preferences... it is kinda how marketing works (lol). They will also avoid overly ugly or normal characters because normal characters are fine in moderation to change things up but should not be the norm due to marketing reasons. Ugly characters can be even more difficult to deal with because they attract a niche crowd but are generally not a strong marketing move (refer to backlash and lack of popularity due to Urgot being too grotesque).
As you indicated yourself... there are many normal female skins that are intended to be cool, and then there are niche skins/etc.
• Nurse Akali is a stripper nurse. No real nurse dresses like that. However, strippers with themed costumes do dress like that. Surgeon Shen is an actual medical professional. (Perhaps, but this is simply filling an extremely popular fetish and Akali's theme is kinda... cosplay. Further have you seen some of her other skins? Her All Star skin is pretty bad ass and probably one of the coolest in the game. I do feel they made her breast too large in the actual model but... still neat. http://images1.wikia.nocookie.net/__...tarSkin_Ch.jpg)
• Cowgirl Miss Fortune is just missing a pole. Her attire is completely impractical I sure hope she is wearing underwear under that flap. High Noon Twisted Fate actually looks like he belongs in the Wild West. Sheriff Caitlyn is wearing hotpants. (Honestly, likely a very popular fetish for many reasons. Filling a niche but this is not her only skin.)
• Officer Caitlyn is in many ways the most disappointing. She is in a position of authority. She is the Sheriff of Piltover. But, she gets a stripper cop outfit. Riot Graves, and outlaw, actually looks like a real cop. No officer in real life dresses like Caitlyn. They’d never be taken seriously. She could have been a badass. Real missed opportunity, here. (Do I really need to answer this one?... Same as above.)
• Battle Bunny Riven is a Playboy Bunny. This is the most blatant one of them all. You can’t even pretend that this is anything but a stripper skin. There isn’t a male counterpart for this. (How long was this asked for before Riot gave in? This one is actually over the top compared to many of the others... but the request for it was very substantial, large enough so to warrant making the skin to rake in $$$ Definitely a fetish skin and more over the top then others but it doesn't go too far.).
• Prestigious LeBlanc is a Vegas showgirl. Magnificent Twisted Fate is an actual magician. (Woopy do... Actually a pretty awesome skin in a non-sexualized way even if it normally is a sexualized theme. In her case it is set up to look pretty awesome and matches her style perfectly as a mage. Also do not ever ever go to Vegas if something as minor as THIS bothers you.)
• French Maid Nidalee is something you’d see in a gentleman’s club. (Same as Riven... Don't ever hire maids ok? Might be sexist.
• Heartseeker Vayne. I guess if Jack of Hearts Twisted Fate is the male equivalent, though again, the male character is fully clothed. (If you are complaining about this one as well then honestly, I can't see how a serious discussion can be made. It is a Valentine themed skin that is rather modest.)
• Mistletoe LeBlanc, Candy Cane Miss Fortune, Snow Bunny Nidalee draw a strong contrast to Santa Gragas and Old St. Zilean. (Can't really take you serious with this comment, I don't even know for certain by this point in your post if you are trolling or not. I'm being honest, I can't tell...)
• Sandstorm Katarina is a belly dancer. (Belly dancer.. no. Bad ass desert fighter? Yes.)
• Red Card Katarina doesn’t dress like any referee I’ve ever seen. Fifa banned players from taking their shirts off. (So a slight twist to make it "sexier" to appeal to the primarily male audience is an issue. Also shirt is on...)
• Kitty Kat Katarina reminds me of Halle Berry’s Catwoman, and that’s offensive on a whole new level. (...Just please... for the love of, grow up. Many of my comments before were slightly sarcastic but I am serious with this comment. Extreme personal bias here)
This is rather extreme bias and subject to matter of opinion. I imagine most women won't find it cool or attractive as well but again that is subject to personal view. I will say, personally I feel the artist simply lacked skill to properly portray what they were striving for (as noted in regards to Tryndamere in past cases).
Due to the length of your post I will limit what I reply to and what I have to say.
Many of my comments were slightly sarcastic because, well your statements were deserving of it.
I find it very difficult to take your thread seriously as I can't tell if you, yourself, are. In fact... I legitimately believe you are trolling in this thread.
Naturally there will be skins that as long as they don't go too far will try to make money off fetish/niche concepts of the primarily male audience but there are those that will attempt to do so or at least balance it for the female and both audiences.
I doubt I will reply to this thread again considering the OP but I may if I have time.