I do weekly 30% water changes on my nano and you should see the crap that still comes out of my skimmer (EuroReef nano). That's with 4 small fish that only eat pellets and once in a while mysis. Not heavily stocked.......yet
Why not use all the help you can get?
If it's not an sps tank, maybe don't need one but I tried the skimmerless sps tank once and although it was good, never got the great color until I added a skimmer.
I'm not saying you can't be successful without but I don't really see the point unless its because you don't have the space.
There have been some threads around RC over the years about how much less active fish are when people have had to keep their skimmers off for a while (days or weeks). Skimmers are great for gas exchange. Keep the water oxygenated if nothing else.