I think I would tend to avoid sexuality rules simply because they constrict characters. I prefer to be the one to determine my own character's preferences.

That's not limited at all. I just don't like roleplays with too many rules. A lot of times, things listed tend to be common sense.

"Dn't tlk lyk dys. If you do, I'll hurt you," is a turn off. I've never come across anyone who has done that and it feels almost as though whoever typed out the rules is either very, very anal or enjoys putting themselves in a position of superiority. As in, "Hey, I can type well! You can't! I will proceed to ridicule you rather than share what I know to help you advance because I'm not a caring person!"

Actually, it's a turn off whenever it's listed that "If you do this/can't do this get out of my face" and there's nothing obvious hinting at sarcasm.

Then there's the classic, "No Mary-Sues/Gary-Stus." Yes, I totally love making flat characters! I know every other roleplayer does... wait... you mean some people roleplay because they like character development?! WTF? Why? *sarcasm*

Just that people enjoy listing the obvious tends to annoy me. I won't always steer clear, but I won't necessarily be excited from the get go. Finding a list of rules longer than the description of the plot and setting is just plain wrong.

Now that I think of it though, I don't always mind reminders.
"Okeh gaiz. The setting is medieval Europe. Pls no astronauts."
In that case, putting constraints on characters is entirely fine. I just don't see when we'd ever come across an entirely homosexual/heterosexual world~

What I feel of that exact rule (sexuality rule) I really can't say. It's odd, to say the least. I cannot find a rational reason behind it (setting: gay bar... okay, I get that one) but in a regular game, it's just beyond me. It would be nice to find out the reason behind such rules. But, I like to live and let live. As long as I'm left to do as I please in peace, I'll grant everyone else the same courtesy.

Edit:// I thought of another thing that irks me. Have you ever been in a one-on-one in which your partner actually posts rules for you? I didn't think I came off as that incompetent.