Characters with odd names is actually a bid of a tradition. Dredd is silly enough when you think about is but there are plenty others. My favourite example is Dredd's current sidekick/protege: Judge America Beeny.
Of course I'm pretty sure making fun of a Judge's name is punishable by a year in the isocubes.
Summer's is beautiful but I think she gets suggested for parts like these from fans because we are familiar with her physical prowess and willingness to do her own stunts. While I am a huge fan of hers I don't think she'd be right for this part. The more I think about it the more someone like Kate Beckinsale would be interesting for Dredd's partner. Dredd's partner actually has a pretty juicy character arc of her own in this film. I would suggest that people take Reverend up on his suggestion of searching for a good script review. Maybe I'll post a link to one later this week once I get time.
I didn't mean to suggest they should
cast Summer Glau, just that I
P.S. Hershey may or may not be in the film. There is an unnamed female Chief Judge in the script and the way she's written in the two scenes she appears it sounds like it's supposed to be Hersey, but it could conceivably be a pre-Long Walk McGruder.
On a related note, anyone have any thoughts on who could play Chief Judge Hershey? I tend to picture Uma Therman in the role but I think that has more to do with cheekbones and that haircut she had in Pulp Fiction than anything else.