Modern TV is too tidy, with everything tied to one or two storylines and everything being wrapped up tidily with maybe one or two cliffhangers. It makes fictional settings cough Star Wars cough seem small and insuler.
Interesting point!
I think a big part of this is because of the internet. Nowadays, if the writing isn’t 100% polished you will get people screaming loudly about inconsistencies, plot holes, or hooks left hanging and I’m sure this has an impact on the showrunners.
That said, I think you can have highly professional/polished writing, and still make the universe seem big and complex. The high quality dramas (Sopranos, etc.) have shown this. Not something Star Trek has every really been good at though.