The Borg Queen said:
How would a "new" uniform use up more replicator rations than an "old" one?
I thought they didn't have any laundry-type things in the future and just replicated a new set of clothes (as and when needed) instead of washing their old ones...
Maybe programming the new style into the replicator was too much of a hastle.
Or maybe the new FC uniform was armored or had some other more energy-intensive upgrade.