The minor DP expenditure simulates two things:
1) The character spent time being resculpted and convalescing, which could have been spent learning a skill or whatever
2) The character needs to adjust to their new body form - this can be as simple as not looking surprised at the new face in the mirror or adjusting how they shave or more involved things as unlearning/learning when to duck because their height has changed.
No harm will be done if the DP cost is dropped.
Best wishes,
Nicholas