Actionscript PersistentService methods should return AsyncTokens instead of void

I liked how the UserService gives you the option of working with AsyncTokens or Responders, giving us the flexibility to design our code whichever way we prefer. Personally, I much prefer working with AsyncTokens. But when I started working with the PersistenceService, I notice all of the methods require Responder arguments and return void. Due to the frameworks I utilize, using responders are doable, but require a lot more code cruft. Is there any reason the PersistenceService isn’t more consistent with the UserService?