Why play chess with ornate pieces, over simple wooden ones? Why don't professional chess players use those large sculpted sets?

Because chess isnt the pieces. The interface isnt the game. If you're attending to the interface, you're being distracted.

When you use computers as tools you don't want interfaces to appear as objects in the world, you want them to dissolve into the tool that they are.

The more I am "impressed" by a menu, button layout, interface, etc. the worse it is at being an interface.

The question is, rather, why do others want to be distracted by the interface? Why do they choose the oranate chess set?

Well, because they're consumers of computers, not users. They barely use them as tools, and so their default relationship to them is one of ornament.

An interface is, almost literally, ornamental to most people. Like a chess set on a mantlepiece.