Even a bumpmap could work well, but displacement maps and dynamic cloth are part of the package introduced with P5. There's still some advantage in mesh-level detail. That fits with materials grouping, and hence the P5/P6 shaders. This one is a simple model that could be used as a base. and so there are advantages in keeping the mesh plain. That's best for transmapped garments, but you could get a whole different range of options if it were a garment with more complicated materials grouping, which lets you unleash different tools.