P-personally, I don't feel like people over the age of the actress should cosplay Hit Girl... I know we do want to show our love for Kick-Ass and unfortunately, Hit Girl is the only really recognizeable female character but what makes her so impressive is that she's so young. The skill would not be as impressive if she were the same age as Big Daddy, right?
I know, I'm short too. 5' and done growing. But... It just feels kind of wrong to me. Anyways, just sharing my thoughts and I'll probably still eagerly take pictures of whatever Hit Girls there are out there, from age 3 to age 83.
Also, yes, cosplay is about COSTUMES, not omg desu desu japan desu. Contrary to popular belief among anime convention attendees, Japan ISN'T the ultimate say on what is X or Y. If you were complaining about people cosplaying Western characters at an anime convention it'd make a little more sense (though I'd still roll my eyes) but Kick-Ass cosplay, if a...costumed character, is definitely cosplay (also, I don't think you'd be making a big deal about someone cosplaying Naruto or Sailor Moon at Comic-con, or PAX, or something). It's not like the Japanese are the only ones to create characters that have eccentric designs. Also, regarding that store? Hello, some of us cosplay characters FROM JAPANESE MEDIA whose costumes simply DON'T have a sweatshop design. Does this mean my Tales of Legendia alternate plot design doesn't count because it's not popular? How about my Persona 4 final boss? Oh wait, these are video games, I forgot those didn't count because you didn't mention them.