Only because the resources are there, there is no need to waste them.
Most of the time people use a really high polycount is to compensate for the lack of a good material shader.
there is simply no need for 200k polys on an asset like this:
http://www.turbosquid.com/3d-models/3ds-max-leather-classical/465612
Ahmmm… And I wish they would build (intelligently) lower polycount models that look just as stunning. 