The point is, that many, many, many people (I'd even say the vast majority) use the term "gay" to describe something as less than desireable. As in, "this movie is so GAY." They don't mean "This movie has a simply delightful sense of lighthearted fun, don't you agree, friend?" If you mean that, that's friggen awesome for you. but that's not how most people (in the US anyway) use the word. They mean this movie sucks.
This IS insulting to homosexuals. Do you mind possibly offending people? If no, then that's 100% your call. Just don't act all surprised when someone is offended by taking a term the way most people use it.
Fact is, it's pretty deeply offensive, and I don't want to be that guy.
If you knew me, you would know I am anything but PC for PC's sake. if you use the term to mean happy and lighthearted, as you twitter around saying you feel witty, and pretty and GAY!, then all power to you. I'm guessing you're not an American english speaker. Do you also refer to cigarettes as "***s" and mistakes as "boners?" If you break a ciarette, do you say "whoops, pulled a boner with my *** there..." Go ahead, feel free, just know that when you do, people might take you as meaning something else, and it might not be smoething you want them to think about you. Whether this is important to you or not is ENTIRELY up to you.
Signed, on behalf of the flippin' homos,