I think that the general plot slowness and repetitiveness of DBZ, Pokemon, and Sailor Moon is a big part of the reason why these three shows went completely mainstream where I live in Canada. I know that's very counter-intuitive, but let me explain.
These three anime shows weren't exactly episodic (DBZ in particular wasn't), but they had that typical benefit of an episodic show in that you felt you could pick it up at any place without feeling lost.
As a high school friend of mine said back in the 90s, "The good thing about DBZ is that if you miss an episode or two of it, it's no big deal because you haven't missed much at all."
(I know this sounds like an insult, but he meant it in terms of plot) This makes DBZ seem
painfully slow for a committed fan of it, but it's actually a plus for more casual fans, making DBZ more accessible in some ways.
I don't think a show like DBZ would work in the modern, internet era though. It's pacing is as much a reflection of its time as it is of anything else.
Another thing with DBZ is that there will probably always be a market for big, burly guys getting into theatrical and
BIG EXPLOSIONS! fights all the time.