Isn't part of the point to go through walls? (Score 1)

Isn't part of the reason people buy wireless routers is so that they don't have to run cable through their house? I want mine to go through walls so I don't have to run that wire through the walls. I mean if I am locking my wireless signal to a single room why not just run cable across the floor instead of buying a wireless router and one would assume expensive paint. This might be an OK solution for a business but if I were a business I would still rather just use plain old CAT-5 to avoid any possible security issues from wireless.