There is something to be said for the peace of mind you get when you buy a 2nd hand car that still has some motorplan left. If this were to be taken away then there is no point in spending more on that 'newish' car and you may as well get something older and deal with it. Or, buy new.
To that end I hope this isn't BMW's way of trying to increase new car sales, because with people becoming wise to the pitfalls of depreciation new car salesmen have a tough job as it is, and it's not going to get any easier.
EDIT
Actually, by taking away the ability to transfer the plan they are screwing their second hand car sales too. I mean why buy an old BMW with no plan when you can get another brand which has this covered.. The costs they are saving would need to justify this, maybe they do.