Ok let's see if I can write my thoughts somewhat coherently
1/ That aint Gwen Stacy. Sure I know the argument, it's an adaption, it doesn't have to follow the source material...blah blah blah...and I agree with that argument. However Gwen's placement in this flick is more than just taking liberties with the source material.....
...with respect to the Spidey Mythos and history, Gwen Stacy has existed (I don't count clones or DIRTY Old Gobby retcons) for a relatively minute time period as opposed to MJ, Aunt May etc.....but yet in my opinion her existence is as big a part of the Spidey mythos as maybe even Uncle Ben himself.....and why is that?....because she was Pete's first love and because Pete's secret identity eventually cost Gwen her life...
...due to the placement of Gwen in the movie, that which made Gwen the iconic character in the Spidey mythos cannot exist...so what the hell's the point in putting her in?........It's Doc Ock with no tentacles!