For the same reason it's unacceptable to dislike straight people.
Just because I'm not on THEIR side, doesn't mean I'm on YOURS.

Because it's wrong to dislike someone for something they can't control. It's the same as disliking someone because they are black.

Because common sense and decency tell us that we should not encourage prejudiced behavior towards other members of our shared society, of which we all belong.

This message has been deleted.

Do you like girl on girl though?

I can't understand why anybody would even need to ask this question? WHY is it unacceptable to be a horrible-prejudiced-bigot? Seriously? Some people need an answer to this? Figure it out you freaking idiot.

It's unacceptable to be a bigot whatever the circumstance.

That's because you're an idiot. Exhibit A: you can't spell. Exhibit B: you're a bigot.

This message has been deleted.

I finally left because I couldn't get a meal at a restaurant or a drink at a bar when I was with a lady friend.
I was often told to "get out of 'our' neighborhood" despite the fact that I lived there before it became a Homosexual neighborhood.
We were called "breeders", told to go back to Texas or Iowa or some other Mid-South state, which is ironic because that's where many of the Homosexual men came from so they could be in SF/The Castro.
We got the dirty looks, the rude comments, the lousy service, the weak pours, ignored by service staff, etc
Maybe it's because you're such a rude person. Maybe it has something to do with the attitude that leads you to generalize all gays as being of one mind, or the fact that you obviously hate that the Castro became a gay neighborhood.
I am the sod-off shotgun.

For sure I was only in the Castro for one night, even if everyone was friendly as can be. Perhaps I was just lucky as I walked down the street holding my wife's hand and kissing her in restaraunts and bars.
But I have had a good number of gay friends along the way and met many more of their friends who were gay. I hate to generalize about any group of people, but I still will.I found them friendly, fun, supportive, open and unjudgmental.
And even not in the Castro, I've spent the evening in gay bars scores of times over the years. Both with a date or my wife who I was affecionate too and solo with friends, I never caught even one comment or instance along the lines of what you mentioned. If anything, I felt the target patrons were happy to have me there and could not have felt more welcomed.
I understand that your experience seems to have been different, so I am curious. In all those 20 years living in a heavily gay area, how many gay friends did you make? Did you discuss these issues with them?