QAF was, I think, necessary for the time. I too immensely disliked the stereotypical characters, but was also delighted to see the show exist at all. QAF spoke to gay people in a way Love, Sydney, couldn't. It was liberating to see gay issues addressed in prime time TV.
That was also its prime weakness. QAF's cast conducted their lives in a gay ghetto, largely isolated from the world around them. It's like saying that Good Times represented the life of average black people in the mid 70s. There may have been grains of truth in the stereotype, but it is by no means the whole truth. I'm reminded of when Nichelle Nichols nearly left Star Trek because she felt underwritten with little to do. Then she met Martin Luther King who urged her to stay in the role just for the profile it gave black people on a popular TV show. I tend to think MLK was right. Uhura may not have been as vital a character on the show as the leading men, but there she was, on the bridge, a black, female officer on board a fantasy space ship. And it meant something! As Whoopi Goldberg exclaimed, "Hey mama! There's a black woman on TV and she ain't no maid!"
That's why I like QAF despite all its flaws. The characters weren't interior decorators or hair dressers, they ranged in age from young to old, supportive to rejecting, and many things inbetween. I think QAF added a complexity to gay life that straight people might not have been aware of. It certainly helped me, living in a small town with no gay community center or even a bar anywhere in the county. QAF told me I wasn't alone, didn't have to be swishy to be gay (I know, I know, but I grew-up around some really negative stereotypes), and introduced me to things I didn't know about (like poppers).
I think like Cabin In the Sky, QAF will come to be seen as naive, simple, stereotypical, and patronizing, and yet it has opened doors and raised awareness among some in the straight community. On the whole, it's done more good than bad.