I'm not especially sure, except the issue of keeping Bruce's ID secret, why he can't just be Dick Grayson. It's not like he really has another life; his attempt to pretend at one, going to the functions Bruce would've and so forth, seems to chafe on him. But really, does anyone think of Dick as having a secret identity as such? I mean, in the same way Bruce or Clark do, i.e. a double life?