Considering the ACTUAL crossdressing in the game lasts all of 3-4 minutes, it's funny how a good 30%+ of the fan art revolves around it. But I agree, it adds to the humor and awesome here.
Honestly, it'd probably be better if Yosuke and Yukiko swapped outfits, if only for their battle skills. Then again it's kinda impossible to match all the characters up like that.