Now let me get this started. Halo 4 did a hell of a lot better than Reach when it comes to commendations, but they still are not perfect. They should be there to both encourage players to go outside of their comfort zone, and reward them for doing well at how they like to play. The problem is that they only do the former. They force you to go outside of your comfort zone to get the rewards such as armor.
In 4 each commendation has 5-7 levels in order to reach mastery and then you get the armor that that commendation holds. What I propose is making it so that each commendation has something like 10 or 15 levels until mastery, but you only need to get to level 5 to get the armor for that commendation. That armor would be the reward for going outside of your comfort zone. The reward for being good at how you like to play would be increasing amounts of XP/CR based on the level you have reached, just like how it is now.
That way it will introduce you to new styles of play without forcing that style down your throats.