Joe Straczynski here (speak the devil's name and he shall appear)....
I think there's an inherent problem in the discussion based on the several terms being conflated. Lots of TV series, American and otherwise, had broad arcs t them prior to B5. The difference was in the degree of pre-planning and the use of certain tools like foreshadowing. Usually, on these shows, they'd get together at the end of one season and/or the beginning of the next, and figure out what they wanted to do, or undo, keep, or lose. It's the difference between deciding where you want to drive before you go, and making it up as you drive.
B5 was the first weekly series to use the tools of the novel -- introduction, rising act, complication, climax and denouement, one per season -- in a television format, which required that you work out all of the story ahead of time so that you could use those devices properly. And over the years, it stayed relatively close to that design, even with a number of bumps along the road.
Dr. Who (of which I am a fan) had its ongoing arcs, but they tended to vary from doctor to doctor, series to series. The closest parallel to what we did on B5 was Blake's Seven, where you can definitely see and feel the degree of pre-planning that went into it.
There's no question that once B5 introduced those devices, other shows picked them up, to greater and lesser degrees. But ANY tool, over-used, or mis-used, can become oppressive with time, and that may be the case with story arcs in SF. Now, it seems, you have to create these vast, elaborate arcs if you want to be taken seriously, which I think is a mistake. I think you need both variations.
I didn't create B5 to say "this is the way SF should be done," I created it in that style because that was what I wanted to do, the specific story I wanted to tell. If there were tools there that others could build upon, all well and good, but it wasn't an object lesson in Here's How It Should Be Done Henceforth.
Which is why, for instance, of all the DC titles I could've chosen to start with, I asked for Brave and the Bold, so I could do single-issue standalone stories in an industry dominated by massive, internecine arcs. I think there's room for both...in comics, AND in TV.
