The destiny content vault is something that all players dread. The Vault takes away some of our favorite content, and while I understand that 'vaulting' is needed for the game, it would raise the population to add back content like forsaken and red war, as those were crucial parts of destiny 2, and still remain that way. Many players have been disappointed in the handling of 'vaulting', and feel as if it is bad to the consumer. In conclusion, I think a way to raise the population and overall happiness of destiny would be to stop vaulting content indefinitely, or add back the vault a a free dlc. TL,DR: Stop vaulting content to make people happy.