I just had this thought myself while navigating the market. It's nice to see it was already suggested but sadly no Market Squad or Admin input so far, so here's a bump with my thoughts.

The functional side of the suggestion is easy to understand, if you own all of the components of a Color / Texture pack then you would have the option to repack them. This would primarily aid in listing complete sets of items on the market with the secondary benefit of assisting in inventory cleanup without having to manually add items to a set. In my mind I see a button that says "Repack Amber" or "Repack 128 Textures" when it is identitified that you have all of the components. I'm not big brain enough to make suggestions on the market side but I understand that a "repacked" set would be functionaly identical to a Color Pack or a Texture Pack. Both Color and Texture packs are purchased with ST (with a couple of exceptions) so there still needs to be an incentive to purchase the packs with ST. Maybe there could be a cost associated with repacking the items? Or a tax applied to purchasing or selling a repacked set on the market? Again, not big brain enough to weigh the pros and cons here but I'm keen to hear feedback from Market Squad or admins.

Edit: Brain blast. Maybe it could be just market side, no actual repacking of items. Just being able to list "Full X" for X price if it is identified that you have a full set of something in your inventory. I imagine this would get spicy considering you can list both active and inactive items so there is a chance you list something you're wearing without being aware. Good thing this is the suggestions board and not the solutions board