I didn't find BS's characterization of the nobles less fleshed out than RJ's nobles of similar narrative status. Sure, RJ fleshed out some of the "big" nobles, like the ones who went into direct conflict with Rand, or who became Rand's stewards...but he didn't really flesh out most of the other nobles. I don't think the nobles we see serve any real purpose beyond as a narrative tool, and I don't think that RJ would have fleshed them out much more than BS did, if at all.