All three villains in Spider-man 3 got shafted,but out of them all Venom is the one who got screwed over the most. Although Spidey 3 didn't do Harry justice,at least he had 2 previous films to build up his character and to see some of the emotions he went through. He still had a good bit of screentime in part 3. Sandman had a little buildup too,though not much. We got to see his powers,a bit of his family life and what kind of man he was. He got to fight Spider-man at least 3 times during the film.
But with Venom? We got next to nothing. The character himself is clearly Spider-man's most popular villain(and one of the most popular of all time),and he ranks in the "unholy trinity" of Spidey's greatest enemies(Goblin/Ock/Venom). Yet,Venom himself recieved only about 7-8 minutes of screentime,most of which was with Topher's face showing?! There was no explanation of why,or how he could block Spider-man's spider sense,or how he even knew about Spider-man,MJ or Sandman. Plus,Raimi and co. had him asking for Sandman's help in destroying Spider-man,which Venom wouldn't have done. Plus,there was no calling himself "we." I mean,that's a major characteristic of Venom,and they never used it! There was also no terrorizing Peter and MJ,or any of that. His voice while wearing the symbiote wasn't threatening or scary at all(it was just Topher). Being one of Spider-man's greatest enemies should've granted him a great fight scene against Spidey,but instead they fought for maybe,2 minutes and then to make sure he'll never return,Raimi's blows him up so completely that there's not even a corpse,or even a tiny piece of symbiote left.
I don't know if it was a combination of too many storylines and characters,or Raimi not liking him,or both. But,Venom deserved SO much better.