I'm sure we would've found out more about him in the sequel.
And I don't think Bale was "wooden" in the first one, but I have to say, in this sequel he was just okay.
About realism vs. over-the-top in comic book movies. It depends, realistic approach can work if the material allows it. Like in the X-Men movies, I think they weren't too over the top and it worked, even though the comic books sometimes go way further than that. On the other hand adaptations like 300 or Sin City couldn't/shouldn't be done any differently than they were. And I think Batman could work as a more realistic kind of comic book movie but not like this. They have to show more gadgets, more "cool stuff" and effects. Like others said, this could be an ordinary action flick too if they switched Batman for an other character... So, I hope they'll change some things in the next one.