I have a very strong opinion *against* unlocks.
I bought the game, let me enjoy it as I wish, don't water down my gameplay by arbitrarily restricting weapons/equipment selection, that's only ok with single players games when they introduce new mecanism, in MP, you should get everything right away.
Make it optional or something, no reason to help experienced players (know the game, know the maps...) with even more bonus (better options), it's STUPID and LAME.
(Of course your opinion may vary )
I agree 100%. It makes sense in single player. In multiplayer it is just an annoying mechanic to further benefit those that play a long time. If the game is well developed skill will reward those that are familiar with it. If skill doesn't differentiate the players then the game is poorly made IMO.