The majority are freedom houses that should be subdivided into tenements and turned over to the people, unless there is specific reason to keep this particular house as a museum, in which case this is what should of course be done.
This sentiment I happen to agree with very strongly, although I think it is important that a great many of them be preserved in one respect or another for their value as artistic expressions. For some people I can imagine large homes being well-deserved. Still, the number of individuals and single families with so much money to throw around that they can afford to buy a mansion ought to be minuscule so long as there are folk who lack the basic necessities for pursuing happy lives.
Aside from that, I enjoy looking at them and, if one day given the proper (albeit highly unlikely) opportunity to do so, might well be inclined to reside in a small portion of such a building.