Casino had a relatively old cast, too. It's probably one of the reasons it was heavily criticized, even though they said it was because of the violence. If younger actors had played Ace and Ginger, the critics probably would have been more friendly to it, despite the violence.
I'm glad Scorsese didn't ruin this by writing in a role for DeCaprio or someone just to appease critics and get a younger audience.
De Niro was in his late-forties. Why would his character need to be older? It made sense. Pesci was around the same age. Maybe he could have been a little younger, but, again, not a noticeable issue.
De Niro, here, looks decrepit. It's a big blow to the credibility of the movie. Not to mention his recent career choices.
