Bungie needs to allow both options in order to satisfy both PvP players and PvE players. The current material exchange, although convenient for strictly PvP players, doesn't make sense. It takes 5 minutes to farm for 20 materials, how long does it take to earn 10 marks? If the crucible rewarded higher marks per match, I would have no problem grinding it there, but 3 marks for a win and 2 for a loss is just not enough. It takes way too long to max out crucible marks each week. Bungie needs to allow both options to satisfy all players.