I've no problems with an EXTRA option to play with man/man, woman/man or woman/woman, totally no problem with, on the contrary
I'm a male gamer and if the option is in, I probably try ALL different options and I very like playing with a female character ! (so nice to "look" at !

)
But I like most of playing man/woman because it seems to me more "balanced" in some way ... just my opinion
Edit:
Of course : this EXTRA option can improve the replayability