I still use those other legendary weapons. If you watched the recent video of the guy 1-manning the Crota raid, he was using Fatebringer - an older legendary weapon. Many different scenarios require many different types of weapons. As such, we need somewhere to store them until they're needed. I knew very early into the game that Bungie said they would continue to support it. I didn't realize by support, they meant take 7 months to give us 4 more general spots in the vault....