To clarify the above, as far as I am aware, Wharton Admissions does not consider the new format of GMAT so much of an improvement that they would require all applicants to take the new format to apply (or favor the new format over the old).
In essence, as long as Wharton Admissions feels the old GMAT gave them adequate comfort to help assess whether a person might be able to handle the academic curriculum at Wharton, the old GMAT will be honored just as well as the new GMAT.
To use a very rough and crude metaphor, a ruler might be a better measure of length than a piece of string in determining whether a fish is long enough to keep or must be returned to the ocean. But both could be sufficiently effective in accomplishing the main purpose: helping to assess whether or not the fish should be kept or sent off.
PS - I do not mean to imply that candidates are just fishes :)