The whole Dredd never taking his helmet off thing basically grew over time to the point where it almost became a running joke (in one issue Dredd keeps his helmet on in the bath for Grud's sake!) certainly in early Dredd strips it was implied that he was hideously deformed in some way, but this seems to have been dropped over time. Now it's more of a statement. Dredd isn't a man, he IS the Law.
Of course any 2000AD fan realises we saw Dredd full (facial) frontal for several weeks in a row in
As for the casting...well the ideal Dredd is obviously Clint of about 30 years ago, and my own personal choice would have been Clive Owen, but Karl Urban? I wouldn't have thought of him, but now he's announced I like the idea, I like the idea a lot! Right sort of age too. Not too old, not too young. Also not too famous but not a complete unknown.
For the record though, and as someone who started reading 2000AD with Prog 219!, I had to say, I don't think the Stallone film is quite the abomination its made out to be. Very flawed but MEga City 1 looks the part, and Sly isn't that
bad, and as for Rob Schneider, it isn't like the comic Dredd hasn't had a succesion of comedy sidekicks. Max Normal? Walter the Wobot?