I think that a lot of people look back on dungarees with rose-colored glasses. Many enlisted personnel thought they were uncomfortable, ill-fitting, and likened them to a prison uniform. The first two complaints are likely due to changes to the average shape of an American since WWII. The fact that the uniform regs had strict guidelines on where you could stop, and that an overzealous chief would frequently interpret that is thou-shalt-not-ever-be-seen-in-utilities, didn't help. It also didn't help that many a chief would require his men to have perfectly ironed utilities with military creases in a material that didn't crease well, despite the fact it could only be worn on the base and while transiting in a car. I have heard countless stories like these from sailors who used to wear them and they are universally happy that they are no longer a required sea bag item.
I think that if we offered to go back to dungarees the overwhelming majority of enlisted personnel would vote no. While I personally shudder when I see a couple of sailors in blueberries walking around the mall - mostly because the blueberries just look awful in general - it is better than the draconian rules we had on our working uniforms up until then.
Improving on the dungarees/utilities was a good effort, unfortunately we are royally screwing this up. The new potential uniform looks promising, I just wonder why it took 3 iterations of uniform changes in under 10 years to get there. While the type IIIs are just fine and look infinitely more professional than the type Is, I do scratch my head at the decision to use a button fly vice a zipper. Like seriously, wtf.
One concern I have about the new 2-piece FRV is whether they will disintegrate in a couple of months like the FRV coveralls do. Whatever material they are made of wears down rather quickly at friction points (armpits, crotch, belt loops, pockets where mechanics put tools, etc). The FRV coveralls, being an underway uniform, we tolerate a bit more wear on them. They also are relatively cheap in the supply system (under $40). The price of replacing the two piece uniforms frequently to keep them looking good when the armpits and belt loops start to fade vice outright rip is going to make the bean counters want to change the uniform again in short order. For reference I have old coveralls that still look pristine but the new FRV coveralls don't last more than 6 months before looking like they are unserviceable to wear off the ship (if such a thing were actually allowed). Oh, and to put a cherry on top the FRV coveralls shrink at least a full size in the wash.
As for the fire - if you're fighting a major fire you'll be in an FFE. If you're not in an FFE, you're probably already dead since the smoke alone will knock you out. The flame-retardent design criteria is overblown.