What I noticed as the difference between the TOS movies and the TNG films was that (at least with the first 4), the scope seemed far more epic. In TMP, we see the unveiling of the Refit, and we catch up with the characters as their lives once again converge together onboard the Enterprise. McCoy was out of Starfleet, as was Spock, who was undergoing the Kolinahr on Vulcan. Kirk was Chief of Starfleet operations as an Admiral, and Decker was now the captain of the ship. In WOK, it had a "nautical" feel in it, with the music of James Horner, the many references (bot visual and spoken), and the uniforms really made it feel like the crew was part of a fleet (as opposed to the pastel pj's they wore in TMP!!). SFS was the saddest for me, as the Enterprise was destroyed, but in the fashion of being epic, it allowed for the all time epic instance of Kirk bending/breaking the rules: he STOLE the Enterprise!!! By admission, TVH wasn't as epic per se, but it was a fun comedy, and you have to admit: Spock saying "damn" every 5 minutes was hilarious.
With TNG: it didn't have the same quality of being epic and big: the crew was pretty much transplanted from the tv series to the film without much change, and the Enterprise D was just the same old ship, which got wrecked. No sense of them being people with lives, but just still doing what they were doing when we last saw them.
Speaking of the ships: the Enterprise -E, while a beautiful ship, just wasn't given the same treatment as the refit, and the ship was too agile for my tastes; it conveyed no sense of its' mass, especially during the Borg cube battle in First Contact. When a ship that big moves with a sense of being big, no matter how agile it may be, it gives it an air of being grand and large. But none of that happened; it just seemed to lack the grace that the Refit had in her movements.
In the end: the TOS films had the sense that the crew were legends as was the Ship, but that they were also people who lived. TNG just seemed to me like a feature film add on to the TV series and lacked those qualities. Yes, Goldsmith returned for the TNG films, but even then the soundtrack lacked the elegance the TOS ones possessed. But then, perhaps we are expecting too much from TNG and remembering TOS too fondly.