Yeah, I took a swing at that one in "Bait and Switch" with an Orion petty officer with Starfleet Intelligence who complains that there's nowhere to put a concealed weapon in traditional Orion garb.
Of course, every Starfleet uniform except ENT has the same problem (no pockets), so there you go.
JMS commented about that on the "Babylon 5" DVDs.
So he explicitly wanted the EA unforms on the shows to have pockets and zippers so the uniforms feel more "real" and more like uniforms than costumes.
The costume designers for probably Enterprise thought the same.