I'm gonna steal from
Genten here and post a rant on tsunderes because they frustrate me as well.
What is it?: Tsunderes. I want to be specific here in that I'm referring only to characters that are attracted to a male character and know that they feel that way but refuse to let it show and instead are hostile to the point of being violent. I don't count characters that are initially hostile because they have other emotional issues and later warm up to a character, nor am I referring to characters that are cool or indifferent, the kuudere. Tsunderes in my mind run hot and are violent despite their attraction to somebody.
Worst Offenders: Louise of
Zero no Tsukaima always sticks out to me as the most un-redeemable example but Houki of
Infinite Stratos has been getting on my nerves lately and I was not a fan of Taiga of
Toradora!
Variants: Characters like the kuudere that are cool or indifferent to somebody they actually like I personally find endearing. It's the openly hostile characters that get on my nerves.
Why is it Popular?: If I understood this maybe it wouldn't annoy me so much. I do know that some people find a girl who can't be honest with herself cute. They like it when a guy can push a girl's buttons. I also have a suspicion that some people like the idea that girls who are hostile to them secretly have a crush on them.
Reasons why I hate it: How much time do we have?
A lot of what turns me off to the tsundere is what I see as the origin of their hostility. They like a guy, they know they like a guy, but they refuse to show it. It often feels like this stems from a feeling that the guy they like is inferior. "How the heck could I like that loser?" The tsundere either personally considers the guy inferior, or her friends do. If it's the former then why are you attracted to him? Maybe he's not as inferior as you thought. If it's the latter then why are you hanging out with people like that? I just find a character that displays such an attitude to be completely unsympathetic.
The other major issue with tsunderes is that once they make the transformation from tsun to dere all is forgiven. If I was in such a position I would not forgive somebody so easily. I would be thinking "You treated me like crap for months (even years) and now you expect me to return your feelings? Fat chance." But for some reason as soon as the tsundere shows her soft side it's all rainbows and unicorns and nobody ever calls her out for the BS she put everybody through leading up to this. I can't stand to see characters like that get a free pass because some people think they're cute.
Notable Exceptions: Fujibayashi Kyou of
CLANNAD is the only tsundere character I've encountered that I could really get behind. (not like that you pervert) Her tsun side was not particularly violent (towards Tomoya anyway). She beat the crap out of Sunohara regularly but she didn't like him and he usually deserved it. She didn't lash out to hide her feelings but instead was only hostile when she was trying to protect Ryou or Botan, which made her tsun side feel much more realistic and legitimate than the typical tsundere.