Baz is what DC wants for J.Stewart.
I will speak bluntly , DC needs a more diverse set of characters, and they have shown this by making attempts at gender, sexual , and ethnic variations with different degrees of success.However they are a old company with a lot of old , white, traditional characters.
Unlike marvel - every introduction of a non white character is viewed with immense attention , wondering what this stoic company will do with a non white hero.
Now while we may or may not admit it , ethnic peoples often live in less than ideal conditions in america (historically).Whether it be the early Italians or the hispanic today - they have different experiences in this country than most of their white peers.
I believe that while J.Stewart is black in skin tone - he may very well be the most "bland" or "vanilla" of the Lanterns.By doing this they did not risk a backlash but still moved forward progressively ,but that only gets you so far.
America and the world views the treatment of ethic people in the USA in a negative light , especially the history the country has with black segregation.However as of right now the feelings towards people of Arabic background is not quite as sensitive.
Lets say you take the Simon Baz story and you change a couple details, lets say he is black and from a bad neighborhood.A street racer, a thief, a potential murderer, with tattoos and a superhero mask that looks like a balaclava.Do you think there would be some sort of a backlash?
I think so , and I'm not sure DC would run that story ... at all, despite the fact it is a premise which is interesting , and lays out potential for conflict (which in essence is the heart of story telling).
To sum it up, J.Stewart is avoided because he was a tool, to add diversity to the DCU while adding very little as far as character.
Is he more interesting than :
the Cocky Hal Jordan
The Brash Guy Gardner
The creative Kyle Rayner.
The answer is no
He is safe, and no artist is chomping at the bit to play it safe.