"1 You have Meshes.
2 You have Meshes that's SubD.
3 You have Meshes that's SubD with Displacement Maps.
4 You have Meshes that's SubD with Vector Displacement Maps.

The higher you go the better they look."

 

Yes.

But only if you know how to create a displacement map that is good enough to compensate for the lack of mesh detail of a SubD mesh.

And so far, I perhaps have seen only two or three displacement maps being made for Poser meshes that I would call "professional quality".

 

If you have hobbyists morphing a single mesh over a wide range of bodytypes, "built in" mesh detail is just more practical than "painted on" detail.

The "built in" will work with every texture map, every shape and also won't interfer that much with vastly different rigs.

Again, those "Pro" meshes are one-offs and everything is tailor made for just that mesh.

A Poser mesh has to withstand a lot more "abuse" by users who not always know exactly what they are doing.

A muscularity morph can go from 0% to 100% with a simple dial spin and any problems can be easily fixed with a swipe of the morphbrush.

A professional grade displacement map needs a lot more know how to be customized.

The problem is not finding the most efficient or elegant or most "pro" way to do things, but finding the solution that delivers the most useability to the average dial spinning Poser user.