Seeing Spider-Man 3 at Wal-Mart doesn't affect my opinion. I see Batman Forever, Batman & Robin and all of those great ****** sequels, but they don't bother me either

t:
He was killed by the man in the first movie if you don't pay attention to a film filled with one giant retcon
But, let's pay in mind Spider-Man 3's retcon; the only major problem if Sandman is the killer is that Spidey let him go. Yes, it's a HORRIBLE move, but the film forced the forgiveness theme throughout the film, so at a thematic point, letting Sandy go makes sense, it's just not something Spider-Man would do and it contradicts the 'With Great Power Comes Great Responsibility' motto because Sandy isn't being taken back to prison. Although, to say letting Marko go is a downside to Spidey's origin, or at least the part pertaining to Uncle Ben, it's not. Peter Parker went through countless lessons during his time as Spider-Man and keeps remembering those special words said by his uncle. He is Spider-Man and has gone through enough trials to already be Spider-Man. The retcon doesn't really kill Spidey's origin at all.
Making Sandman the killer isn't the issue, the retcon is. Sandman could have very well been the killer if planned out just as much as Black Cat's father was the killer in The Spectacular Spider-Man, so at least be clear if you're referring to the retcon as the problem.
But...to gripe on Raimi's trilogy when you yourself said we have two more films to go for Webb's series. Let's not say Raimi butchered his series so far when Webb could as well butcher his version. And he didn't do that well the first time at bat anyways, imo.