By avoiding the word, you avoid insinuating the target's gender is part of the issue, and/or avoid insinuating that the target is effeminate when they "should not" be, i.e. you avoid homophobia.
It's not.
>You generally wouldn't say a man was "screeching".
Sure you would. I've never seen it posed any other way or with any other intent.
I am under the impression that, on average, men's voices are lower than women's voices. Hence some connotation.
Doesn't mean men cannot screech, though. Just that there is some reason for making that connection, so at least some folks will make that connection.
I fail to understand why using these words is bad, though.