Except the 80% money back is a compensation for people losing the house over being away for a long time, not getting rid of it willingly. If it was meant to be a means for people who bought a house to get some of their money back upon relinquishing it, they would have made it so from the get go.
People just need to accept that this is how the system works for now. If they're not willing to lose money over relinquishing the house, they should think carefully before getting one. A gil sink is a gil sink; it's not meant to give you back your money upon relinquishing.
And anyone who thinks they are so entitled to their gil they think it's okay to have someone pay for their purchase on top of their own, that speaks for itself.