I think Silver was doomed because he was introduced as a hero character, but was tricked and was sent to kill one of the good guys who was also the main character of the series. Silver was supposed to be a punk with a strong sense of justice, but this would only work if he was fighting only actual bad guys with no deceit. This is different than Shadow. He was presented as an antagonist and "dark" version of Sonic. Shadow's tragic past and having his heart changed at the end was subversion. Not to mention he was the biggest focus of the game. Silver wasn't even the main focus in his debut game. Shadow himself outshined Silver in it.