Usually what dance groups want is a sprung floor. This flooring system allows for some cushioning for the dancers. If they were dancing on a concrete slab, the forces of the dancers stepping across the concrete would be the same as with a sprung floor, but sprung floors slow down the moments of impact, diffusing the forces exerted on the dancers ankles. That makes it not only more comfortable for the dancers, but less likely to cause sprained ankles.
On top of that, a portablemarleydance floor is usually rolled out on top of the stage floor for dance events, because there are plenty of dance motions that are painful, if not impossible to do on a wood surface.