Good god, this thread makes me all kinds of angry. The OP and the replies alike. So, so, so angry.
Things that make me angry about this thread:
1) People are allowed to cosplay anyone they want.
2) Girls can cosplay boys and vice versa, and some really do pull it off well -- yes, even the MtF crossplayers.
3) If cosplayers want to wear something uncomfortable due to weather or impracticality at a con, who's going to stop them? Hell, I'd even argue it's not cosplay if you're not uncomfortable in some way.
4) Cosplay, IMO, is not about having the face and body for the character, but making the character work for your face and body type.
5) There's no rule to who can or can't be cosplayed, either. Original characters may annoy people or get called Mary Sues, but they're still fair game even so.
6) And finally, people are allowed to cosplay anyone they want.
Cons almost always have rules about decency and weapons/props, but other than that, anything is fair game. All the judging going on in this thread makes me unspeakably angry, though.
Yes, it's a very expensive hobby, and it takes practice and effort to pull off. The general rule is that the more money, time, and effort you're willing to pour into your costume, the better it will look in the end. The ones who don't put the effort in are the ones who wind up looking like **** and getting plastered all over the internet to be laughed at, but it's the same as any creative hobby in that it takes practice and dedication to get "good" at. Usually, compromises between character appearance and individual cosplayer work best, though, IMO.
No one has to like cosplay or any/all of its concepts, but this thread just makes me want to take the gloves off on everyone. If you don't even go to cons and just look at pictures on the internet, you don't really have any room to talk, frankly.
And, let me just reiterate this for good measure:
PEOPLE ARE ALLOWED TO COSPLAY ANYONE THEY WANT.