If I was flareless on the Rubicon I wouldn't have dented the rear quarter or at least not even close to what the flare did. But if I didn't have the front one rip off and serve as a buffer between rock and fender/door the pass side would look much worse than it does now. So on my toughest trail to date I have a thumbs up for flares and a thumbs down
As for looks: without them it looks more like a trail rig and does give a bit of clearance, similar to a built 4Runner. I personally do like the look with them and enjoy the mud they catch and keep off the sides of the rig. I had a 93 pickup with some 10" wheels on it when I was young and it through crap up the sides all the time.