The thing is, if you got a free transfer/move from one housing area to another, and it was 1 for 1 as you want, then you only have a limited selection for that 1 for 1, your plot is graded and you payed a set price different from other plots of the same size.

You can't have that with a tiny selection of plots... and if they let you skip the grade and just pick any plot of the same size, you could buy the worst plot at the cheapest price and move to the best plot for no charge, and for large houses there is a much bigger gap in pricing of grades, 40,000,000 start for the worst and 50,000,000 for the best (LB plot 6 vs Mist plot 5), right there you saved 10,000,000.

Plus we would then have people buying plots to resell for 100% profit, they could then sell you a plot, then move to a new one for free, see? someone just made lots of Gil from you and you bought them a new house too.