It is more common now. The parent post is probably referring to the 90's where this was ground breaking. I was in kindergarten while this was on the air and a friend of my parents would tape it for us. My parents would allow me to stay up to watch these episodes. My first true science fiction love along with Star trek TNG. Babylon 5 has a lot of concepts that have stuck with me over the years.
Season 1 is slow and terrible in some places. Particularly the CRT monitors look very dated along with the clothing which is supposed to be futuristic but screams 80's. The rest is good from the plot to many of the actors (Garabaldi, G'kar, Londo, and Delenn) come to mind, but many others were also great.
I think Delenn sells a female powerhouse role so much better than any other actress I've seen in science fiction. She is intelligent, thoughtful, funny, a master politician, and even a little scary at times even though on the whole the character reflects serenity. Her arc is great too. There are so many good Delenn scenes that depict her character's wit and badassery that it is hard to choose a favorite (dealing with G'kar early in season 1, defending the station on a Minbari battle cruiser, challenging a military dictator on her homeworld).
"Only one human captain has ever survived battle with a Minbari Fleet. He is behind me. You are in front of me. If you value your lives, be somewhere else!"
Game of Thrones, though adaptations where the source material is spread out over multiple seasons are probably cheating a bit.