I think for a few reasons. First being you don't say no if you get asked, like any of the iconic roles, like say Bond, they ask you do it. Secondly if its successful it will afford him more power, more power to do projects he wants to do, it will open more doors in terms of finance and opportunity. Think he had a big struggle to get Argo made, wont be the case if this works out.
I honestly think in The Dark Knight Rises, Bale's Batman was becoming a bit stale and stagnant. He was vehemently overshadowed totally in The Dark Knight and whilst he played a fine role in Batman Begins, he still went at it with broad strokes if you ask me. I enjoyed Bale's performances, I really did and I think he's a great actor, but as I say, I found his definition of Batman/BW a bit too polarised. (Which is something that I said from Dark Knight).
Clooney was far too pedestrian, and the movie was terribly produced, terribly scripted and Joel Schumacher should just hang his head in shame. However, as I say, Clooney didn't explore the character at all, he was there as a reader and for all intents and purposes, Schumacher's Batman's are all about the
interplaying ensemble than anything else. So I mean, whilst people severley criticise Clooney's Batman, I don't blame Clooney himself, I blame the film itself. He did what he could with what he had at the time.
Practically, I'd pretty much say the same about Kilmer. What Kilmer did was to create a pastiche of a character, struggling with the dynamism of his own character, and his need for duality. Whilst this didn't really come across so much in the film, it was all about BIG characters, BIG actors portraying the characters that they fleshed out. What is interesting about Kilmer's role is the very distinct themes where he almost fights to keep Batman and Bruce Wayne apart.
But then, for me, personally, Keaton played Batman/BW to a tee. Slightly quirky, slightly sinister and almost with a naive charm that shows the duplicitous nature of Batman/BW. His physicality and manner is what sold it for me, even clown-like in his ways at times.
I think each have their own merits to a degree, and whilst personally I do have favourites, professionally I can objectively see the performances and governing dynamics of each outing and I think they should all, more or less, be given their own status within a series.
Affleck is a good choice, he has a good bit of stock since Argo and The Town and whilst I didn't like him when Armageddon came out, he has certainly grown on me as an all round performer.
