Certainly a real theft for transplant purposes wouldn’t have been so crudely done. While a Dahmer-like murderer is a possibility, I think the next most likely motive is a murder to obtain body parts for ritual purposes, as I believe is still theorized about the so-called “Thames Torso” murder in the UK.
However, since external parts such as hands and genitals would be of value for such purposes, and they don’t seem to be missing from the Philly victim, it’s a little less likely. If he was killed for some specific ritual purpose, though, I guess they might have just taken what was prescribed.