
I never realized how few mafia games I played, and I always saw GTA as a gang series, not a mafia series (to me the difference is mafias have some form of order, like a large business, where the gangs in GTA are more analagous to contract workers, if that makes sense), but you raise some good points.
Finance management sounds like an interesting component to have in such games, though I'd probably prefer it be optional.