They shouldn't be allowing upgrades for anything from the past except non raid exotics in my opinion. People need to move on and get new gear it's why games like this are (or should be) fun when there's an expansion it's a whole new hunt for new loot. Bungie is shooting themselves in the foot if they allow us to take gear from the past and level it up. It's gonna mess up progression and the new weapons won't even matter.