The gender of the character doesn't really matter per se whenever I think of a concept. It always comes secondary compared to whatever I conceptualize. If the character's identity, race or ethnicity plays a factor in how I roleplay that character, then, I take consideration of that.

Your concerns are far more valid for 1x1 RPs whereby the individual who makes a interest check specifies that they want the character to be of a specific gender (Or hell, in worst cases, the player to be of a specific gender). I often find the latter to be more annoying given the anonymous nature of the internet. Don't ask me to do a psychological analysis of why the heck anyone would want to RP with someone of a specific gender.