And I say,
Bounce a graviton particle beam off the main deflector dish
That's the way we do things, lad, we're making shit up as we wish
The Klingons and the Romulans pose no threat to us
'Cause if we find we're in a bind, we just make some shit up
- Voltaire, "The U.S.S. Make Shit Up"
Building a coherent universe is a big responsibility - after all, it is a universe with all the detail that the word implies. Fortunately, creators don't have to go into detail on everything, or even most things; coherent universes can be built with broad strokes and implication, and the nature of those people and places and things that are focused upon in the narrative can imply a great deal about the society they come from.
Use too many broad strokes for too long, though, and you're in danger of a universe that doesn't look particularly like anything much at all. While some creators might be able to pull off that sort of thing, for most people too many broad strokes means that detail is lost. It's particularly easy to fall prey to this sort of thing when you're working in a shared universe - something like, say, Star Trek.
One of the problems with most of the Star Trek series came from one of its strengths - the starship setting, which meant that at the end of every episode the crew could leave those particular problems behind and not have to face them again. Even when those problems were solved, it was as if the solution was wiped from everybody's mind after the credits rolled because you certainly wouldn't see it show up again. Generally, if a writer was in a jam they - or, for that matter, the script editor who filled in the instances of [TECH] in the scripts - would create some particle or technological doubletalk to make the problem go away, but they wouldn't be filed away for later use. It's not as if every problem the Enterprise encountered was completely unique, but there's rarely if ever any attempt to try solutions that worked in the past. The same thing happens in terms of background details - in many shared universes, it seems, the preference is for something new to be created at need out of whole cloth rather than building upon something that's already been established to exist.
The problem with this is it leaves a long spoor of one-use solutions and settings, and makes the universe sort of like a puddle a mile wide but a millimeter deep; it appears to be big and dynamic and thriving, but it's the authorial equivalent of a set on some soundstage. Because authors didn't take the opportunity to build on what came before, there's a veneer of artificiality to the whole thing.
It's easy enough to correct, and particularly in the modern day - when fans maintain meticulously detailed wikis of their favored properties - there's a lot less reason for writers in someone else's shared universe to be unaware of firm foundations. For something that you created yourself, it behooves you to go back through every once and a while and reacquaint yourself with your work; it could be that some minor off-the-cuff thing you established ten stories ago is just what you need to help resolve something today.