The iMac is an all-in-one, so I don't think many people will be adding their own speakers (might as well get a Mac Mini at that point). I think most users will

The iMac is an all-in-one, so I don't think many people will be adding their own speakers (might as well get a Mac Mini at that point). I think most users will use the jack for wired headphones, in which case having it on the side makes it easier to access.