Star Trek is one of the best things to happen to television. TOS, TNG and DS9 are 3 of the greatest TV shows you could ever watch.
..but the films, whether TOS or TNG, are mediocre apart from a tiny select few of them. The film series is a dumbed down, frequently half-arsed parody of Star Trek and while I'm glad it exists so we get gems like Wrath of Khan or Undiscovered Country, I have little time for most of them in comparison to the far, far superior TV incarnation.
DS9 is my favourite Trek and I'm grateful it never made it to the big screen. A committee led Hollywood continuation would have pissed all over the finale.
I do think First Contact is fun action shlock but considering TNG is the show that gave us beautiful TV sci-fi like The Inner Light, it just isn't good enough. On a similar note, Search for Spock and The Voyage Home are fairly bland compared to the 15 or so best TOS episodes.
It isn't a question of whether TNG is suitable for action blockbusters. It's a question of whether any Star Trek generation is suitable for that.