TWOK is really the first part of a trilogy. Taken as a whole, the TWOK/TSFS/TVH trilogy is bolder, grander, more dramatic, and ultimately more satisfying than most individual episodes of TOS. Looking at them that way, we see a symphony that overshadows the faults in each of the individual films.
Long story short there, the TOS films managed to transcend the limitations of TOS on TV. They took us places far beyond where we'd been before. They freakin' killed off one of the most popular characters in TV history, destroyed the Enterprise,
and then brought it all back by the end of TVH.
Did the TNG films ever manage to do something similar? Nope, not even close. There is certainly no overarching story across even just any two of the four films. As individual films, they play like souped-up versions of TNG two-parters: The Best of Both Worlds, Data's Head,
I mean Time's Arrow, Gambit, Unification,
etc. In the case of GEN, since it's the torch-passer, arguably it gets to be a souped-up combo of two two-parters, say like Unification
with a dash of Relics,
And before you say, "But TNG blew up their Enterprise,
too," and "They killed off their popular character, too," well, you know that the reply's going to be, "Been there, done that," dontcha.
Long story short, where the TOS films went far beyond what their show did, like cranking it up from 4 to 11, the TNG films were only like cranking it up from 4 to 5, 6, or maybe all the way to 7 in spots.
Further, while the TOS films at least managed a sentimental finale at the end of TUC, the TNG films went out with a whimper at the end of NEM. Nothing really artistic going on in the TNG films by comparison. Nothing even worth fighting for after NEM. At least the TOS films had some fight left in 'em after TFF.
The TNG films play like an empty cash-grab, if you look at it that way, that just got played out.
When I go back to watch TNG, I'm always going back to the show, never to the films. In the case of TOS, I go back to both.