INS wasn't too favourably received/did less BO than expected, I think the cast were only signed for 3 pictures so the 4th had to be re-negotiated (apparently PStewart came close to not doing it), I think the studio wanted either a new 'movie' crew or an all encompassing crew (presumably combining casts from TNG/DS9/VOY) but Berman wanted another TNG only film, bringing Enterprise to tv probably delayed production on Nemesis too
I don't think there was any desire to do a 4th immediately after the last one anyway as has happened with GEN/FC/INS but those issues probably added another year on (abit like STID getting delayed by all the other stuff JJ, Orci etc was doing)