That's the whole point though. Retainers can't do anything important in game lol. Sure they can go farm stuff but then again if someone got an alt to 50 promptly they could just as easy use those 2 retainers to go farm for them. That retainer won't help people dodge them landslides.
Thus paying for the extra retainer is understandable because just from going from entry >> stand subscription, you only gain optional enhancements to game play.