If you have already have network cabling installed, you can put that cable from the network socket to your RPi or possibly to a switch that is already connected

If you have already have network cabling installed, you can put that cable from the network socket to your RPi or possibly to a switch that is already connected—not all the way directly to the other one, because that cabling is already there. And, yes, if you would like to move the unit outside (e.g. during a party) then wireless is quite convenient. You can mix and match :).