This might be beside the point, but I'm wondering what historical TV shows you're referring to...? Because as I often claim, I watch a lot of old TV, and writers were doing "the black character" and even "the gay character" well into the 80s and 90s. Wanting characters of different ethnicities and backgrounds to be simply 'included' rather than highlighted is more of a recent phenomenon, if you ask me. =/
Also, I would be reluctant to hold up "getting their own shows" as a desirable result or end goal, because at that point it's fairly easy to end up with just 'TV segregation': y'know, where people can start de-legitimizing inclusion along the lines of "if you want to see black/lgtbq/female characters, just go watch that show (where most or ALL of the characters fit into that group), and leave our NORMAL shows alone!"
...That sounds like a step backwards to me.