I would love to see party-based crafts like houses, boats and cakes be implemented whether there are buffs or not. But the buffs and incentives are definitely an awesome idea. It would sure help alleviate the cost of getting those final ranks in.

Another idea I had, which would be better when there's LS housing or some sort of rentable instanced workshop, was a sort of cooperative or time-share crafting for big ticket items. I imagine being able to rent a big workshop for a set amount of time with access restricted to the LS which rented it, and players can go in and help craft bits and pieces of some big project like a caravan, ship, or even a house. Players would be able to work together in the workshop groups or on their own if no one happens to be there, but every successful craft adds towards the collective progress of the project. If the project takes longer than the lease on the workshop, you would be able to renew it the lease or lose the project and progress thus far.

Alas, since crafting/gathering have been demoted to support classes, it'll probably never happen so I hope at least some form of group crafting will be added one day.