Originally Posted by OcStat
It's not like the Sandman has never done that in the comic books.
He did it in the Spectacular Spider-Man cartoon too, but it was well executed there. I think the problem with SM3, or at least that's the feeling I had, is that he was Sandmonster more than he was Sandman. Right in the first battle, which happened so quick, he became that giant pile of sand, groaned, attacked the cops and flew away.
In the cartoon, that came after some defeats. There, Sandman becoming a giant creature felt like a last resort. He needed something big to save everyone from the burning oil tank. It wasn't arbitraty like in the movie.