As I've said before, I wouldn't necessarily be too quick to judge how deeply fleshed out the characters are in Seth Grahame-Smith's script. When almost an entire film's worth of material supposedly ended up being cut, all that material might have helped to flesh out all the characters quite a bit more. Though, sadly, we'll probably never know for sure unless/until we have an opportunity to read the script for ourselves.
And, of course, another thing we have to remember is Warner Brothers' bizarre edict that the DS film couldn't run over 2 hours. So, even if his script had been used, no matter how much fleshing out there may have been in August's script, who's to say how much of it may have also ended up on the cutting room floor?
Material ending up on the cutting room floor seems to be a plague that affects all DS films.