We really haven't. It used to be that gay characters were written as overly feminine, by straight writers bc we were being used as a joke. Actual gay writers in the industry now also write...exactly the same femmy characters into stuff (as someone working on theatre/media industry is quite likely to be a more fem gay).
What I want to see more of before I'm happy: young, interesting gay characters that demonstrate their love for one another without it being a Big Deal, that don't get killed off or only play a minor role.
Atm all the gay characters I see are: * Older men * All femmy, not just average dudes * Get killed off/removed from the story quite quickly * Are labelled as "gay character" but they aren't really shown being gay (making puppy dog eyes at cute guys, or having a boyfriend, etc).
Also lots of shows take shortcuts by having a lesbian character (which is also great to have), but gay men are still far less accepted by society/in media at this point. People would rather see two women kiss on screen than two men.
Are you sure this was always straight writers? It might also be gay creators using certain tropes to sneak in gay-coded characters without stating it outright.