I agree it seems like they have just neglected a huge villian. Harry does become the goblin in the comics, but Norman is such an interesting villain with the Iron Patriot and controlling the void etc. Would have been nice to see them link the marvel and spiderman universe with these together, but doubt that will happen.
They can't do anything as it relates to the Avengers though because of the rights issues, etc. If it were that easy, we could skip ahead and have Spidey, Wolverine, and the Avengers in all one film.