Was it not established that the Enterprise wasn't involved in the Dominion front as they were trying to garner support from outside the Federation to support the war effort?
I think they did that in The Gorn Crisis comic, but there are at least two novels that show them thwarting a Dominion scheme to create their own artificial wormhole.
I'm sure I've read that the loss of the flagship would've done so much damage to the morale of Starfleet that they saw little to no action.
Was the E the flagship?
I'm sure they could find things to spice up Picard without using support characters from DS9.
I'm sure they could, but I wouldn't mind seeing some.