Why Dense UIs Matter
For some UIs, efficient is more important than pretty.
My one hot take on UI design systems is that most of them are only made to look pretty. They are not made to be efficient. They are not made to be data dense. They are not made to be accessible. They are not made to be easy to use. They are not made to be intuitive.
Believe it or not, it's actually easy to make a UI look pretty. There's a handful of tricks that one can apply to get consistently good looking UIs. These involve things like using a generous amounts of whitespace, very light borders and shadows, relatively low contrast colors, etc. As long as your overall UI layout makes sense, these things will make your UI look pretty.
The problem, of course, is that tons of whitespace doesn't work very well for data dense UIs.