I think that these people are missing the entire point of pride flags: the reason why they exist in the first place.

It's not a matter of same-sex attraction somehow being a cause for celebration-- like, "I'm a woman who's into women/man who's into men, so pop the champagne and release the confetti, WOO-HOO!!!"-- but rather, all too often, of shame. Which LGB people attempt to remedy by instilling a sense of pride. Represented by these flags. So we can hopefully feel good about ourselves, instead of bad. It's a respite from the stigmatization of our sexuality which, even today, remains more the rule than the exception.

So pride flags only make sense in this context. They aren't for sexual proclivities (as opposed to orientations), which either don't receive intensive shaming or actually deserve it (hello, "minor-attracted persons"!). As far as other "what-you-do-in-the-bedroom" stuff goes... there's just no need.