Just to clarify, are you talking about turning in for Grand Company seal as opposed to not selling to other players? Your title is confusing if that's the case.

With respect to the augmented gear, that's not "old stuff" yet. It's the best gear available through scripts. Not everyone wants to get the crafted 340 gear because they don't want to pentameld (or can't if they don't have the correct job leveled to 70). I don't think SE has ever allowed items to be turned in for GC seals until higher ilvl items from the same source content can be obtained.