As someone who owns just one personal and just one FC house, I would find it extremely unfair to take ppls houses away which they have owned before the rulechanges. Especially on alts.
And no, I'm not talking about the ones who buy like ten houses to sell them off again. I'm talking about normal people who just love decorating and housing and have worked hard for their houses and spend time working on them.

I dunno, just taking them away would feel so...wrong. :/