Do we
really need it though? Raimi's first Spidey film came out only nine years ago, everyone knows how Peter becomes Spider-Man. Why waste time on re-establishing the origin when it's still very fresh in people's minds? Besides, I don't look forward to the inevitable comparisons between Raimi's way of showing the origin and Webb's way of showing it.
If they choose to go the route of Peter already being Spider-Man at the beginning of the film, then I think that's great. I'd prefer they jump right to the ass-kicking