Aguero doesn't? He does it more than anyone in the league. And how many times does Van Persie cut in from the right and shoot? I agree with the rest of what you're saying, though. Get Jelavic to worry about scoring goals before anything else.
Aguero does it because he's utterly amazing and has the ability to, but his primary job is to be a goalscorer. If the goals dried up, he'd be told to get back to basics, Dzeko would play the target man whilst Aguero ran off the shoulder, or Tevez would play to hassle the back line whilst Aguero drops in between the centre halves.
Van Persie drifts wide but he doesn't do so for defensive reasons; it's to pull away the centre half before making the late clever run into space. Those two are for me right up there with the worlds best so the things they do is difficult to compare to Jelavic.
I think the primary job of a striker at Everton is to get to the first ball if the ball is punted long into the channels and close down the opposition full backs in possession.
If it were me, I'd definitely say to him "you know what, just stick it in the net lad, Vic and Naisy will do the running today." and let him play how he wants against Oldham at the least. Show him a bit of faith; that you believe he's going to do the business.