So why have the icons corresponding to the number of players? What I'm asking is - why not just have 2 spots for dice for each resource; one spot if you didn't roll (or want to use) a 4, and one spot for a 4, for each resource.
One spot isn't enough in a 3 or 4 player game, because 3 players can generate each resource (two in the regular spots, one in the 4+ spot).
I think you've got it now. Yes, there are 6 dice spots in the 2 player game, and 9 in the 3+.