Why would you need much more external filtration with a bare bottom tank? Live rock and a good skimmer are all you should need and a refugium harvesting macroalgae is an added bonus.
A bare bottom tank, IMO
, makes it easier to remove detritus. You (meaning the tank owner) become the cleanup crew by siphoning out detritus that has collected on the bottom. With a sand substrate, proper sand sifting creatures are required to keep the upper layers "loose". Also a sand substrate becomes a home to many little creatures...amphipods, copepods, bristle worms, spaghetti worms, micro brittle stars, etc. You will definitley still have these creatures in a bare bottom tank, but IMO
probably not as much as if you have a sandy substrate.
You can have a good looking and healthy tank either way.