Femininity is not in itself a bad thing. The problem is when it’s made compulsory for one gender, and denied to any other.
There you've got it, in a nutshell. To argue otherwise is to be femmephobic.
P.S. Here's a heartening forum topic regarding the controversy of
whether or not boys can wear pink. Other than the OP, everyone else in the topic saw no harm in letting boys wear pink and/or like other "girly" things.