You're ignoring the part where he's holding her arms down and forcing her legs open. He's no different than the "dragging women off the streets" rapist, he just didn't need to do that in this case.
So my answer to that is below; just in closing the wikipedia article insinuates [1] that the reason that any of this was reported to the police was because the women involved wanted Assange tested for STDs, not because they wanted him prosecuted for rape. The Chief Public Prosecutor didn't think it was rape at the time.
This seems pretty reasonable, and to me says that rape in Sweden is potentially about as serious as a traffic violation - there was potential, if other things had gone wrong in a somewhat unusual conjunction of events, for someone to have been harmed. An unsavvy woman (potentially those involved) would have been completely unaware that she had been raped.
I'd need to see something new, but while Assange may have committed a crime in Sweden he shouldn't be stigmatised. The word rape, in this very specifc case, is being used in a very technical manner and is clearly a slightly arcane legal term. Maybe discipline is required, but it isn't clear-cut what sort of penalty is needed. Again, I think an apology and some time with a doctor seems in order. Maybe a fine. Possibly this could be handled outside the courts. An extradition is uncalled for.