Aside from what others have mentioned - maintenance/upgradability. I own a home in Costa Rica, which is basically all concrete. Try upgrading your building with Cat6 ethernet when you have concrete (vs wood/sheetrock).
It's definitely not protruding in my home... and it's all conduit in the walls.
Most useful was from my attic (not livable space) up in the trusses to my basement utility room. When I convinced a local WISP to use my roof for a back haul and access for the neighborhood it saved them (and me) from running wires all over the outside of my house and was a quick, clean install.
Conduit is common in commercial work here, but almost never in residential.