It depends on what you're doing. If you're streaming full sized blu ray rips from nas to tv for example or even transferring 20 or 40 gig files then wireless can be more of a pain than anything else. There is also a security risk with wireless as opposed to hard wire. A good system will operate on both principles. Wireless for the smaller hand held devices and hard wire for the work horse situations. I wouldn't even consider going strictly wireless.
That is exactly how I have my house wired. I have coax and 2 cat6's going to each spot where a tv will be. And I have another cat 6 in key rooms for a computer. In addition to my wireless.
Even if you are on the right track, you will still get run over if you just sit there.