Now the game design being sexist seems a different issue but it's not. The game is exactly what its audience wants it to be. Blizzard is an ethic-less company, responding only to market factors. If the audience is a bunch of morons who jerk off watching cybering blood elf girls, then the blood elves are designed to be sexy. Anything else would be bad business.
The problem with this idea is that the demographic he's talking about is only part of the game's audience.
There is no comprehensive research about female MMO/WoW players. The BBC did a survey that estimates that 40% of EQ2 players are female. Nick Yee used data from WarcraftRealms that showed only 16% females, but that's only people who gave their gender on that fansite, so it's surely an under-representation.
Even if you think the BBC's estimate is high, Blizzard's chosen imagery still turns off millions of potential players (not just females, but also males who don't like this art style). The current state of the game is bad business.
But if they are an ethic-less company that only responds to market factors, why would they do this? Because their art choices are driven by their own preconceived notions, not market factors.
Blizzard is a boys' club. Guess how many female artists, out of at least 16, worked on Starcraft 2, according to the behind the scenes DVD? One.
Blizzard's elite art team, responsible for most of their concept art? Zero females. In fact, it's called Sons of the Storm.
Remember that photo of the entire community relations team that came out a while ago (y'know, where Netheara became a sex object for thousands of frustrated internet teenagers by daring to allow her photo to be taken?). There were 2 women in that crown of 2 dozen.
So a bunch of boys make a game. Of course the art will cater to boys, because that's what they think looks cool. I'd also argue that a lot of socially insecure guys end up devoting their lives to video games to the point that they work at (arguably) the top developer in the world. We could go on and on all day about why there are so few women involved, and I'm going to sidestep that issue for now. What I will say is that it's hard to put out something females would like if you don't have a single female on the team.
They have no proof that their portrayal of gender "sells" or doesn't. The game might sell just as well or better if they had more variety. They aren't responding to market forces in this case. It just doesn't occur to them how unappealing some of the art in this game is to a huge chunk of their potential audience, because to them, half-naked buxom women and burly, inadequacy-soothing men have "concentrated coolness".
If they really wanted to improve business, they would give a wider range of options. And in a lot of ways, they have (dwarf and troll females, gnomes, goblins), but those options are poorly represented by NPCs and especially by major lore figures. There's absolutely no need to get rid of the impossibly-burly males and buxom chain mail bikini babes that appeal to the insecure boy market. Don't take anything away from them. Instead, add more variety to appeal to a bigger audience and bring in even more money. How about a dwarf female faction leader in heavy armor, built like a tank? Or a trim and cut human dude in nothing but a chain loincloth (and a bow tie) as a faction leader (just to make it even given sylvanas's outfit, after all)? Why are the worgen led by some old guy when they could have a young topless male werewolf with washboard abs (talk about a ready-made audience!)?
As it stands, Blizzard is failing to be an ethic-less company responding to market forces, at least when it comes to their representations of gender.