As a "converted" DS9 viewer;
When I first saw DS9 I didn't like it simply because you would get lost if you tried to see the odd episode here or there.
This is not just due to the long-runing arc but also to the complexity of the characters and their interaction.
On TNG (NOT one of my favourites) the characters were much easier to follow. Interactions were far shallower so it was easy to pop-in for an odd episode here or there.
Their is no question that once you watch DS9 in order it is a completely different world.
It's interesting how for years this was pretty much the default position for network executives about serialized storytelling, that most people aren't going to catch ep after ep, so things must be simplified. But now in the age of DVD boxsets, online streaming, DVR recordings, the public is MUCH more receptive to the idea of TV being watched in a particular order like the chapters in a book.
IMO this is a wonderful thing. The old format was an absolute drama killer and held TV back from its full dramatic potential for decades and decades. You used the word "shallower" and that's precisely what it is. It's more than possible to get amazing, excellent standalones out of that format, but nigh impossible to get genuinely interesting characters who change and grow and develop.