First up. Moderators please don't move this to Crafting forums. I've already made a similar post there regarding 8 trait crafted armours and this is more aimed at the seeming surprise that many players have with regards to needing to group with people for some activities outside of dungeons and the necessity of "toning down" some of the later vet' levels in the upcoming patch.
As it stands 7 traits stands "empty" with regards to being able to craft any sets. As do 1 and 2 for that matter.
My suggestion would be that you add a good number of crafting stations and have them all have sets that are
group related. Similar but different to the type that drop in the group dungeons. eg boost to group health etc or reducing mana costs and so on.
I recognise that that would be a pretty massive undertaking so an alternative might be adding to the existing stations and have a 7 trait set where the "special" ability affects everyone in the group but otherwise identical. A third option would be to add new sets to the "normal" stations but have a skill requirement of 50.
I think this idea would have people recognise earlier that grouping is a
good thing and has tangible benefits for doing so