Nolan and co could probably make a good Batman film that works without any of Batman's rogues, I'm sure they could find a way to do the third film without the Riddler, Catwoman, Scarecrow, Penguin, Two-Face, Mr Freeze, Mad Hatter, Killer Croc, Bane etc. They could come up with a brand new villain never seen before in the comics, does that mean they should just because a possibility of a good Batman film without his rogues exists?How about this argument.
The third film CAN work well WITHOUT robin...even if the possiblity of a good film with robin exist.
If it can work WITHOUT robin, then there is no real need to add robin.
If they want to develop the Batman/Bruce Wayne character and progress the universe that they are adapting (not creating) they should cover all the major elements of that universe.
