I'm going to defend the people you guys are thrashing here. Point-by-Point:

1. Not everyone is a pro costume maker. I would imagine that the girls in the above picture at least took SOME valuable time out of their life to put something together. I mean they have weapons, right? It's not like they put on lingerie and some elf ears.

2. Blizzcon is in California. I don't know where you guys are from, but in SoCal, it is a social norm for women to show skin, and a lot of it. Maybe a skimpy outfit wouldn't fly as much in, say, Toronto, but this is Southern California. The outfits above show skin, but they are not trashy or distasteful.

3. Would you be more accepting if they just threw on jeans and a t-shirt? I feel that putting people down because of what you perceive as their lack of effort is very unfair and can even be hurtful. What if they took some time to make those weapons they are holding?

4. Compare the top picture to the lower picture. You have a sea of mostly guys wearing t-shirts. Why is there no aggro or anger over their lack of effort?

TBH, I feel that hating on people for their clothing and costume choices is extremely shallow and closed-minded. Not everyone is going to make a 10-foot Kel-Thuzad costume or a 2-ton Mistress of Pain setup. Heck, most people aren't even going to go in costume. Just enjoy the people for who they are, having hatred or anger towards people for that might mean that you close yourself off to some people who might be really cool and fun.