What Robert Pattinson is describing here is part of the franchise filmmaking churn.
As Robert Pattinson discussed on Variety’s “Actors on Actors,” Twilight was already laid out, the novels had been written and the studio had already decided what it wanted.
So the creative latitude and influence he previously enjoyed with his characters in in smaller films was not available to him in Twilight.
Franchises like Twilight are brands unto themselves with hundreds of millions of dollars staked on their success.