Destiny is the only series I've ever played where I literally have to find other players to group up with outside of the actual game. I've always found this to be ridiculous and inconvenient. Optional matchmaking for every single pve activity affects no one that doesn't want to use it. Easy, normal and hard modes should be in all pve activity. Everything from story missions to raids. Sometimes people are in the mood for a challenge, sometimes they just want to relax and blow through content while feeling powerful and badass. Everyone has a different style of play and skill level and these tiers cater to all of them and at the same time nothing is sacrificed. The higher the challenge, the greater the rewards and loot.