ok only a suggestion 
and why should buy people all the houses..... not every1 have soo much money to have 1 or more house
I don't know why people do it, but I've seen it happen before, so I think it should stay where it is where you can only own one house. I mean, if you see a house you'd rather have you can always sell your current house and buy that one. There really is no good reason a player should own two houses or more.
Anyways, Thank you for your suggestion and please have a nice day.
Regards,
Brendon