It was plotted and written in the era where a plot of the week had to carry an entire episode. Main characters can no longer be allowed to get entangled in a non-critical event for a full episode just to reveal something important about them for later. Writers have to be more clever than that. There's no room for "this time on B5, a rebellion/alien/telepath problem/encounter."

With 22-episode seasons like the original, I bet a good writing team could do something like this:

Season 1: building up the world, revealing the Shadows at the end

Season 2: Shadow war

Season 3: proxy wars

Season 4: Loose ends & Consequences, including Thirdspace and the telepath war. If there's enough material, maybe even move the telepath war to a 5th season. I always wanted to see what happened to the Vorlons' favorite telepath.

There should still be room, in seasons 1 and 2 especially, for some cute but essentially irrelevant subplots like Green vs Purple.