Was thinking that it could be a good idea to be able to "store" exotic class items like you can for exotic weapons and armour. So make an extra section of all the combinations and players can only retrieve what they have already collected. This would go a long way to providing more vault space for everyone. Obviously not fixing the problem entirely, but would be a step forward and easy to implement. Also it would encourage players to play the other characters. I personally haven't collected other class exotics because of the storage issue.