Well, here's my take on it, as a woman who plays a lot of games.
I think that many games' representation is inherently sexist, though this might not be intentional. Notice I said many, not all.
The problem isn't as simple as sexualised armour or revealing outfits, though. It's the fact that established female characters in many video games are treated like sex objects. In many games, even when women are put in the spotlight for action scenes or something like that, they're sexualised. Their movements are super 'sexy' and fluid to make them look beautiful. Is it a bad thing to look beautiful? No. But when you then have your male characters just slugging people with punches or gunning people down (not shirtless or naked, of course) with just pure power and efficiency in mind, it makes women's action scenes or just movements in general look exaggerated.
There's also the whole 'romance' thing in a lot of games. Chances are if the protagonist is male, you'll have some kind of love interest. This isn't always the case, of course, but it is common. And usually, even if that love interest is a badass in her own right, she usually ends up needing to be 'saved' by the hero, and then immediately starts falling in love. This is becoming less common, but it's still prevalent.
The other thing is that many female characters are exaggerated simply in their appearances. I'm not saying that men aren't - I'm honestly tired of every male protagonist being this buff muscular dude without an inch of 'give' to him at all. However, you can't deny that in many video games, women's bodies are just...completely unrealistic. Big chest, wide hips, slim middle, to an extent that most women can't even achieve with tons of working out.
I could go on.
I might also add that the solution to heavily sexualised female characters is not sexualisation of male characters. Honestly, unless the game is about fucking people, you shouldn't be objectifying anyone. I'll use Dark Souls as an example. Male or female, most of the time, the armour you wear doesn't conform to stretch around a woman's tits. It just fits and protects like armour.
And whether you think the whole 'bikini armour' thing is offensive or not (I certainly do, I hate that scanty and barely protective armour is 10x better than armour that actually covers your body), you have to admit that it's unfair to women to give them this horribly sexualised armour and depiction of the female body and then complain when they say it isn't fair. The argument of "It's a fantasy, it doesn't have to be realistic" is bogus, because you shouldn't be forced to wear a crappy skin-tight suit or a revealing bikini that somehow has better defense than actual armour. And I know you aren't actually forced, but if it has better stats, what are you meant to do?
I just personally find it a bit insulting when men see women's complaints about video games and say to 'get over it' or 'it isn't sexist because WE like it'. If women don't like it, if the actual gender being objectified thinks it's offensive, then that's what should matter. It's easy to say that you want men to be sexualised as well, but what if you had a female protagonist that went around kicking ass while she saves defenseless, shirtless men from harm and makes them fall in love with her? I'm exaggerating, but I don't think you'd be very happy. So there is a problem, and whether you think the fix is to sexualise both genders or neither of them, you have to admit there is a problem and that it needs to be fixed somehow.