This is the kind of knee-jerk reaction I've been reading in pretty much every news article about this casting. This news JUST breaks, and already everyone thinks it'll be horrible. How many actors that ended up being great in a role were at first jeered in the initial casting news? RDJ? Ledger? Even Bale for that matter.
I realize that everyone is entitled to their own opinions, but Affleck has come a long way since he first started in the business and piling that baggage onto this news just seems a bit asinine.