TOS lasted three seasons and six movies...TNG lasted seven seasons and four movies. There's probably a balance in there somewhere.
I do tend to think that TNG didn't translate that well to the big screen and that the producers giving in to Patrick Stewart's demand for Picard to be more of an action hero didn't really help matters. I understand that there is only so much you can do in a two-hour action film, but I still kind of think TNG worked better as a TV series. Nemesis
was simply putting an end to something that really wasn't working as well as it did on the small screen, IMO.