It is an intentional design by Bungie, but I personally think it is horrible as it does not allow for adaptability. Particularly in PvE, unless you are precognitive, it hinders you. In truth, I think it applies to PvP as well because you don't know ahead of time what arsenal the opposing team, or even your own team, is bringing into battle. I understand the need for balance, but it is a terribly implemented method of balancing.