Ellen had just come out. The Matthew Shepard tragedy was national news. Will & Grace debuts.
The most pivotal years for gay acceptance in (in America) recent history?
These years seemed to be the turning point for how mainstream America viewed gay people. Agree or disagree?
Melissa Etheridge riding high on the charts, don't forget..
The 90s are so weird. The early 90s feel like a looonnng time ago, yet the late 90s still feel relatively recent to me. I can't believe how much time has passed.
The turning point was actually Lawrence vs. Texas, the 2003 Supreme Court case that decriminalized homosexual acts and, by extension, homosexuality. This led directly to Massachussets leading the states on marriage equality and, ultimately, United States vs. Windsor, the Supreme Court case that just struck down DOMA.
Culturally speaking, OP, the events and trends you listed had an impact as well, but it's hard to really dicern which events actually affected a change in people's attitudes (Shepard's death, which brought the long-festering reality of gay bashing into the mainstream) and which were reflections of attitudes already present in the culture (Ellen's coming out, which ultimately resulted in her show being cancelled).
Will and Grace will be remembered as both a watershed moment and a massively toned-down and prettied-up, unrealistic portrayal, much like The Cosby Show. It is significant and it did have an impact, but much of its themes and portrayals already read as dated and inauthentic.