I'm aware of that Killahmatic but there's a lot more personality, so to speak, in these comments than what we saw in GI. He discusses the absolute basis for each character; not who they are and what they do but why we play as them. There is value in that information.
"One of the advantages of the three-character system is you can have characters who, if they were the only protagonist, would be far too flawed for you to find appealing. With other equally flawed protagonists, but flawed in different ways, I think it gets more understandable."
I find this to be the most interesting thing he said because it directly relates to all three of them. I was pretty bored of Rockstar forcing these psychotic-yet-morally-correct characters upon us. It's almost like they were so intent on making the main characters likeable that they forgot what they truly were. More often than not, the villains are better characters than the heroes, and the heroes that are unrelentingly evil - think Walter White - are even more interesting.