lol... when I was taught as a student to use an insulin pen, I was told to squirt a little bit out but I thought it was just to make sure it works (hate not being able to see the insulin actually being administered). Priming the needle make sense, though!
We draw up our insulin from multi-use vials where I work. I'm pretty certain you could teach an intelligent primate to use an insulin pen OR draw from a vial. If there are problems with insulin administration, I would blame the system and not the nurse, e.g. pens not being labeled with patient's name. Administering the insulin is not rocket science. The most difficult part is making sure you know what dose to give.