Loads of girls think suits are hot. Most likely because they are related to having a job, money, power i.e. things many women find attractive in a man.
When they look like Neil Patrick Harris, all I can say is SUIT UP!
Not all the time though. I'm also into kind of grungey rocker guys with long messy hair wearing skinny jeans and t-shirts, but sometimes, a man in a suit just looks good