TNG adopted the suggestion made by "Tribbles" writer David Gerrold in his 1973 book The World of Star Trek
that any new series should feature an "away team" (he'd used the term "contact team") because the captain of a starship should not be endangering himself by routinely leading landing parties as Kirk did.
Another major difference, of course, was that Picard didn't repeatedly get involved with alien women (or female androids), as Kirk had.
In those two important respects (and probably some others) TNG was simply more sensible
- which could be said to work against it as an entertainment, as some here have suggested.