I'm seeing a couple of posts circulating about the gay 90s and this movie. The above is a very good summary, and I think it's worth adding a few other points.
This movie got made because Robin Williams said yes to it (and it's important that Gene Hackman did as well). Williams in the 90s was a mega-star of a type that's not present in the current media environment (maybe Tom Cruise, but I personally think that's echo from his salad days). Even his flops made money on the back end in the video rental market, which also doesn't exist anymore (streaming is different). Hackman was on the other side of his A-list career but still Hollywood nobility if not full royalty.
Playing gay was considered career suicide in the 90s. There had been a number of actors who put lie to that belief stretching back decades, but this was Williams and Hackman (yes, being on screen next to a gay character was enough to get you blacklisted) saying "screw that" and doing it anyway.
Being gay and out was career suicide in the 90s.
Nathan Lane had a really nice gig going for himself. The Lion King put him into the Disney rep company with people like Williams, Bette Midler, and Whoopie Goldberg (check their IMBD list from the 90s--they were making bank at Disney).
Lane didn't come out until several years later (nice summary: https://deadline.com/2024/06/nathan-lane-robin-williams-advice-coming-out-birdcage-1235975010/).
I don't want to imply that this was a Sorkinized moment where everything changed because of one thing, but this was a very important movie that caused real movement in the needle on queer acceptance.
It also proved that there was a market for films with gay characters, which had the knock-on effect of gay filmmakers being able to find distributors of their gay-themed films. Which meant that more people than ever (queer and non-queer) got to see representation on-screen.