Sad but true, I believe the rough barrier serves as a warning to cartballers. This may not seem like a big deal for members, but remember, every Monday there are 100 or more nuts driving around on your course who don't really give a damn...The damage carts do around a bunkers can be severe. I was playing in an outing last year at Morris County when our forecaddie, trying to be helpful and move the cart to the next tee while we we were putting, drove the cart over a mound and then right into a bunker he forgot was there! It made me sick...
Also, for a course that has rough barriers and would like to change, I think it is a really big task. You would have to strip out all the bluegrass and re-plant or sod with bent. And you can't just do a bunker or two, you have to do the whole course, every fairway bunker and green complex, so the look is consistant.