A friend of mine I mentioned this too actually thought of a interesting concept for it (and they don't even play lol). If SE doesn't want to hand out inventory space that easily, give a free retainer after X amount of months of sub time. That way people who are playing longer and have more stuff piled up will have the room. Meanwhile those who -must have- the extra retainers ahead of time can pay for them until their sub time catches up. Obviously not a perfect solution but I thought it sounded pretty good.