First, it's not 1:1. You can spend 50 marks to get 100 mats, which convert back to 10 marks and +50 rep. That's 40 marks for 50 rep, which is 1.25:1. (Apparently I initially screwed this up in my post, too, so we were both wrong.) Second, it's not nothing. There are lots of players who've hit the endgame and have nothing meaningful to spend their marks on anymore; allowing both buying and selling of materials gives them something to buy--another 200 rep per week before the nightfall bonus, in exchange for a currency they weren't using anyway. Finally, though, the problem is that materials drop from patrol bounties and daily missions now, at a rate of 26 per day. So it's an extra 100-125 rep per week for doing nothing at all, [i]before[/i] you factor in rep gain from spending marks. I don't know how carefully they've planned out the reputation economy, but I think it's plausible that an extra 200+125 per week might have made someone over there nervous.