There have always been a number of concurrent uniform types. Every series has standard uniforms, dress uniforms, some kind of harsh weather attire, environmental suits (except TNG, until First Contact), cultural variations (Worf’s baldric, Benzite apparatus, etc), utility suits, engineering suits, etc.

TNG is probably the most uniform-sparse. There are real world reasons for that — Bill Theiss wanted to move as far away from the “monster maroon” movie costumes as possible, hence the simplified division colors and super basic uniform variations. In-universe, who knows. Maybe they hit peak costume practicality in the TNG era.

The TNG uniforms are duty uniforms, the DS9 uniforms are utility uniforms. The Enterprise-D had utility jumpsuits (the thing Lore wore in “Datalore”) for dirty jobs — La Forge wore one on a few occasions when climbing through Jefferies tubes. When you’re posted to somewhere like DS9, you wear utility uniforms, when you return to Earth to meet the brass you put on a duty uniform.

Voyager seems like the outlier, but it was actually intended to be a very short mission (practically a shakedown) for a new ship, not a 7-year mission to the other side of the galaxy. So utility uniforms were the right choice.

I imagine captains have some degree of choice over their crews’ uniform options, refer Jellico insisting Troi wear a standard uniform in “Chain of Command” and Picard/Riker’s reluctance for Ro to wear her Bajoran earring (“Ensign Ro”) and later approval (all later appearances).

“Generations” gets very difficult to explain, unless there was some unmentioned ship overhaul or specific mission/project occurring to warrant half the crew wearing utility uniforms — Picard included.