Here's a cool post by Riot's Michael Maurino on the thinking that goes into women's character/armour design in League of Legends in 2015.
We as artists at Riot have different ways we interpret power fantasies. We express it in different way. All of them are valid I feel. Whether that's Riot Zeronis making extremely badass and conventionally sexy ladies, to TheBravoRay who designed Kalista and definitely bucked trends there, to myself who likes diving into what actively challenges conventional gender roles.
I think my own understanding is evolving, I think Riot's understanding is evolving, and I think the games industry is evolving. I think that's absolutely fantastic, and I'm so happy to throw my hat into the ring when appropriate.
Armoured ladies aren't the only solution to gender diversity in roles and character development. I think each power fantasy has a niche and can be expressed in so many ways. In the end it all works! It's all about what works best at what time in what context!
One of League's biggest issues visually is that it's all over the place, with no single unifying style or trademark unifying the game's various character designs. Sometimes that counts against it, in that it's difficult to point to a LoL character and say, yeah, that's definitely an iconic LoL character (like you can with, say, DOTA 2).
But other times -- like with this -- it works in the team's favour, as by gradually adding to LoL's roster and tweaking stuff over time, they can roll with the times and tweak things without having to scrap the entire game's style at once.
Maurino's thoughts on why they're doing it should also be noted, bolded, framed and hung on a wall:
I'm also really delighted that other companies have made intentional strides to expand female character pools. Not for the sake of appeasement or agenda, but for the simple fact that so many amazing character possibilities lay undiscovered or have not been capitalised.