Your point 6 is the only one I disagree with, as it's actually quite useful.

After, for some people, a male playing as a female is a turn-off whilst others care more about the story and the character and don't mind who plays as the female, as long as the role is filled.

Having the (Playing something specific) tag is so useful as it means you can just click on a post and not have to try and figure out if the poster is after someone who's a specific gender or is just after someone to play as a specific gender. I mean, yes, someone can just pretend to be another gender but if you've previously posted prompts, it's hard to hide the truth and I don't want to mess around with a secondary roleplaying account.