A content finder is simply a better way for solo players to experience parts of the game that they may not otherwise see. Perhaps they are a new MMORPG player and have no friends they are starting with (we were all there once), or maybe they just prefer a no-commitment style of playing and is willing to settle for pick up groups constantly. Or, perhaps they are raiders and have a linkshell but want something to do between events. There is literally no reason not to want it unless your goal is to prevent other people from playing the game how they want.