I'm actually surprised VOY didn't change uniforms without an explanation.
As for DS9, the new uniforms suited them going into the Dominion War. The Starfleet Attire and Uniform Department has to justify its existence somehow
R. Star wrote:
Pretty much stated. They redesigned the uniforms for First Contact and to maintain continuity they had to switch the DS9 crew over. Which was funny since you'd see the extras in the old uniforms for a number of episodes until they had enough made for them. Heck, the Admirals didn't get new uniforms until season 6.
As for Voyager, they kept the old uniforms since they were separated from the Federation. Though by they were aware of the uniform change by Message in a Bottle and definitely by Pathfinder.
Ah yeah... because of the movie.
I should have put that together.
It made sense they didn't have new uniforms on VOY because for a few years, they had no contact with Starfleet. When they did eventually contact Starfleet, the people back home had the new uniforms, but the VOY crew kept their old ones.
In the movie "Nemesis", Janeway is shown wearing the new uniform.
I think VOY handled it in the correct way. They could not have possibly known about new uniforms. By the time they did know in Pathfinder, Message in a Bottle, etc, who cares? They were out in the middle of nowhere.
And Janeway needs the replicators in tip top shape for her coffee~