More heavilly stocked tanks (and fed), no matter what the size, will have more protein to remove...thus a protein skimmer is usually necessary at some point. But, people who go w/out skimmers usually just need to keep up on much more frequent H2O changes. There is not one right answer on the protein skimmer debate, IMO, as there alot of ways to maintain and take care of your tank.
Personally, I had the Remora Pro HOT skimmer with the larger pump on a provious 75g lightly stocked FishOnly-LiveRock tank and it did well. I still have it, and am planning on using it on a Oceanic 30g cube reef tank soon.
Good luck -