Sadly, TNG was running out of steam -- for all the reasons stated above. Considering how good DS9 became, it's clear that, for TNG to continue, it would have needed a kind of revolution in approach and storytelling. And I just don't think that was going to happen. It's a series that, understandably, "played it safe."I know it's been suggested and lamented about numerous times before but what if Star Trek: The Next Generation carried on past 1994? Would it have prolonged the Trek franchise under Berman or would the franchise crumble at a similar rate it did if not faster? And with at least two out of four TNG movies sucking out loud, that is an indication that the tried and trusted TNG cast could not compensate for poor or repetitive storytelling.
Take "Second Chances," for example. TNG could have completely shaken up its characters and story potential with replacing the Riker we knew with the more ambitious, but less-experienced duplicate. That alone would have changed the whole dynamic of the show, energizing what had become an increasingly stale dynamic. But TPTB weren't willing to take those risks with the "sure thing" that TNG was.
I give them credit, though, for knowing when to change approaches -- and considering we got DS9 out of the deal, I'm willing to accept the end of TNG, as well as the film duds (namely Nemesis and Generations). If TNG were to have continued, I seriously doubt there would have been any significant alterations to its fundamental dynamic or premise -- and the results would have been increasingly uneven, as we saw with Season 7.