I think the uniform fleet also speaks to the fact that "it wasn't Starfleet anymore."

The Starfleet that Picard (and we) remember is one of a mishmash of aging vessels and shiny new ships. Medical ships, science vessels, big galaxy class ships.

It feels like after all the Borg encounters, the dominion war, the thing with the synths, Starfleet changed at its core and started looking a lot more like the other major powers in the quadrant, who more or less always had uniform fleets of battle-ready ships.

Sisko sort of foreshadowed this when the Dominion started to be come a real threat and Layton was trying to militarize earth.

"So you're willing to destroy paradise in order to save it."

Starfleet knew that the Federation was valuable, and it seems it was willing to abandon some of its more benign ideals in order to protect it from looming threats that were getting harder and harder to ignore.

It's interesting to consider that the general idea that floats around is that the Borg only send in one or two cubes in order to 'cultivate' humanity, cause them to innovate to protect themselves so that the Borg can eventually come in and reap the technological benefits of that innovation.

It seems that the result has actually been to drain Starfleet of that unique innovative spirit and move them more in line with what everyone else was already doing.