Whether you have more than you need or you don't have enough, since we can already buy the other upgrade materials we need, why not be able to buy weapon and armour materials the same way? Me personally, I have no use for my vanguard marks, I would like to be able to buy weapon parts without using glimmer to buy weapons just to dismantle them. For those saying grind for it, well why should I have to when I can already buy the other upgrade materials needed.