OK...I don't think anyone is saying there should ONLY be series. The point was that some professor was saying that it was bad, or a crutch, for an author to have a series. If that argument was applied to TV, we couldn't have a series, only single episodes/movies.
I like both - where it makes sense. I really enjoy going back to a known setting and reading different stories, like Bradley's "Darkover" or Anthony's "Xanth". I also really like reading about a single character when that character/storyline is actually progressing, like Ayla in the Earthchildren series. I like single books/stories, like Raymond Feist's "Faerie Tale"...although sometimes I really wish there would be a sequel when I think the story isn't quite finished, like Dave Duncan's "The Cursed". I really did NOT like Edgar Rice Burroughs' "Tarzan" series because it was 20+ books of the same character without a logical tie between the stories...He was a baby in the late 1700's (early 1800's??) and then he was in his mid thirties fighting in WW1??!! Wut? I mean, Tarzan is cool and all, but he's no Captain America!
Cheers,