Couple ideas, some probably making most sense to implement in the next expansion.
1. Incentives to replay the raid. Helping friends is alright, and the raid can be fun in itself (if people don't cheese....) But you shouldn't come away from it without anything. Either have some kind of a "Raid vendor" with Raid Bounties and such. Could be a way of obtaining certain raid gear that won't require you to test your RNG luck every week.
or
Diminish the returns on the raid. First raid of the week gives you classic raid stuff. Second run will give you chances at legendaries. And every run after that just gives you payouts similar to the vanguard strike playlists.
2. Different ways of getting world materials. Farming is by far the worst aspect of this game. Patrol missions should drop mats. Enemies should drop mats. Public Events should drop mats.
3. Stop oversaturing the game with whatever welfare exotics Xur is selling that week. Ways to fix?
I think for next expansion, most of the new exotics should be tied to bounties. The Thorn bounty was awesome because it gave you a cool variation on a strike and gave you a good story on how you got Thorn. More stuff like this.
Perhaps Xur can sell different exotic bounties every week (you can only choose one). Tie it to the lore by having the bounties be missions that benefit The Nine.
ORRRRRRR
Xur will sell engrams instead of set exotics. This way everyone gets an exotic, but it won't be the same for everyone.