Prior to the arrival of McDavid, I believe the plan was for Hall to be the captain and face of the franchise. As years passed and losses pilled up, I think management started to question Hall's maturity and ability to lead the team out of the darkness. He was a great player with the Oilers, but IMO he doesn't really have the personality of a leader. Maybe that is something that will still come as he matures; I really don't know, but for some reason he was never able to earn the respect of the vets in the Oilers locker room. Maybe that was because the vets were all garbage (many certainly were) or maybe it was just a symptom of constant losing - hard to say.
I recall an interview back in the Eakins era where he was talking about personal goals he had for himself (in the midst of another lost season) - point totals, all star etc... I think that mentality took over as a coping mechanism and resulted in many of his teammates viewing him as a selfish player. Regardless, I don't think he was captain material - I just don't think that is a role he's equipped to excel at. Was the trade a good move? Yes, I think Larsson on the blue line for the Oilers makes more difference that Hall on LW. Did Hall live up to his hype? I would say no, mostly due to injuries and losing.