In a non-RM game I am playing currently, the GM and the party leader often discuss things between games, even advancing the game with actions, and I think it's problematic. The GM's intent is to keep things moving quickly but it often backfires because the other players spend a significant amount of time arguing about things they weren't included on. This would be less of an issue if the player was good about sharing the information, but for various reasons he's not. In my opinion, if the GM is going to offer the opportunity to push things forward between sessions, that opportunity should be there for everyone (even though some players will not take advantage of it).
As for circumstances creating a leader, that's certainly true and can be helpful to avoid the same person being the leader all the time. The GM can also take advantage of that to change leaders from time to time, e.g. while the party is traveling with group X, they'll have to at least act like Joe PC is in charge (maybe for religious reasons, maybe he's the military veteran, etc). You can also take advantage of language to change who gets to be the main party spokesman. I think it's useful to change the party dynamic from time to time. In the long term you also have to be aware of what people enjoy and some people will not enjoy always being put on the spot, but it's often good for a leader to remember what it's like for everyone else.
In our RMSS game, the fighter is the long-established leader, the elven mentalist is the gadfly/vizier, and my nightblade is mediator and adviser to both sides. But currently we're in the elven lands where things are different, so leadership has fallen more to the mentalist (who has higher civilian rank here) and the elven paladin (who has higher military rank).
In the RMU game, the rogue is the leader of the uncivilized half of the party, and the civilized half of the party doesn't really have a leader so they do a lot of discussion. When it comes to civilized interactions with the world, the rogue lets the civilized folk figure out how to do things, but once things get into high-risk (combat, dungeon delving, etc), the rogue will take charge. It's an interesting dynamic.