As I understand it, true deep sand beds of 6" depth have a limited lifespan. They are great biofilters, but after 5 years or so start releasing sulfides and toxins, and therefore have to be renewed/replaced.
Shallow sand beds, less than3", still provide some biofiltration (not as much obviously), and can provide habitat for critters that can function as CUC or food.
I'm not fond of the look of barebottom tanks. I like the more natural appeal of a sandbed. I do orient my powerheads to provide high flow across the 3" sandbed so that there is not detritus accumulation.