The thing that I really don't like about Star Trek is that there is very little progressing metaplot. And with the exception of the Borg Threat and the Dominion, very little has changed in the star trek universe.
Especially when you compair that with shows like Badylon 5 or Galactica.
Mind you it when it comes do B5 of BSG, both shows are some thing where if you need to watch every episode. If you miss one, you've lost the plot. And it's extremely hard to impossible to catch the show mid season and understand what is going on. BSG is from the very beginning. B5 is about from mid Season 3 onwards.
Like DS9 tried doing it. But it really annoyied we that in one episodes, every one is fighting and all that. And then in the very next episodes, it seemed that nothing really happened.