SimPE, Sim Surgery and Skintones

So apparently, when you use SimPE's Sim Surgery to transfer one Sim's skintone to another with the "Skintone only" option...


...you end up with results like this.

Shouldn't the skintones affect the heads as well? I can understand that any bodyshapes included with that skintone shouldn't affect the head, but shouldn't the skintone cover the head too? If I transfer the skintone from a Sim with a Pale Classic Pin Up body and skin to another, shouldn't the Pale part apply to the entire Sim (even if the Classic Pin Up part doesn't)? I'm not entirely keen on copying the Archetype Sim's entire appearance onto the Patient Sim, since I might actually like how the Patient Sim's head and facial features are shaped, particularly if I myself did a bunch of slider work to get the Sim's facial appearance just so.


(...like I did with Kileighney Hagg's nose and chin. You're beautiful, Kileighney! Don't ever change. )

So am I overlooking something here, and that's why these Sims have heads that look like they were Frankensteined onto someone else's torso?