Why do you think a 41-year old actor can't portray that, out of interest?
I'm really glad to see your optimism Shadowbat!I am in no way a huge Affleck fan. It wasn't until The Town and Argo that I considered him a good actor. He has matured in Hollywood I his abilities, imo. I am anxious to see what he can bring to the Batman character. Outside of having the look, I can really see him doing a really good 70's Neal Adams styled Batman. Can't wait to see the overall direction they take.
In terms of storytelling we dont have to thread old ground with another origin story and it creates good conflict to have a seasoned veteran angered by such a huge change to the status quo that the events of MOS bring.