Why do we need to identify more genders?

I'm not trasphobic. But I tried to find out reason myself but I'm not able to so I want to know and learn from others and from their knowledge especially from those who identify themselves from any other genders other than just simply male or female.

What is the need to identify more genders? Why can't we keep it simple like I'm a male with more feminine quality in me or I'm a female with more masculine quality in me. Even who takes birth as transgender by birth because of their such genes they also either feel like male or female. So even they can categorise themselves as that. Or we can keep an extra categories for them. So we can keep 3 genders at max. But why we need sis female trans female etc. According to me it does only complicate everything more. Like we don't know we should allow trans female into a female bathroom or not. Using this loophole any male can go female bathroom telling they are trans. Will it be okay?

Why can't we just keep it simple? I want to understand.
Why do we need to identify more genders?
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