It stops being entertainment for some of those who like a dose of intelligence in their scifi movies/series.
It's not about taking it seriously, but making some measure of sense.
The writers relied too much on 'human stupidity' in order to get away with numerous errors they did.
Plus one of the most saddest facts is that they avoided showing a same class of ship more than once because it was previously a hero ship and thought that people would get ... confused.
Almost every Trek show was better in it's initial seasons instead of later on.
In the later seasons, the writers focused less and less on intelligence aspects and began to dumb everything down.
The best example of this is DS9 (at least from my perspective).
The humans behaved essentially like their early 21st century counterparts on that show with much less emphasis on the 'we are better than contemporary humans'.
No one is perfect, neither were the 24th century humans, but it was nice to see them resolving issues without spouting contemporary insults/swearing, reaching for a weapon and losing temper like cavemen.
I cringe almost every time as I see the characters slowly devolving in their behavior.