The only retort I have is when I made the mistake of tool shopping with the wife.
I needed a larger set of sockets, and her idea was to just buy the socket I needed, and not spend the 'big money' for the whole set. 'Because I never know what I'll need in the future'. So buy a new iPad, or not. If you need one, get something that will fit the future, not something that will make do. At least that makes sense to me.
If there are two different memory levels for the new iPad, why get the smaller unless it comes down to cost. Releasing the larger memory, to me, seems a way to future proof the purchase. *shrug*