I think the initial design was for raids to be tiered as well as story missions. So, it wouldn't necessarily have made raids irrelevant, but a series of increasingly difficult challenges. Prob is when they introduced better gear from tower venders, Joe Shmoe is now just as powerful, making vog irrelevant minus vex and fatebringer. To fix, Bungie should allow raid gear and weps to be upgradable with the guardian to any new level cap. That way raid items, i.e. end game content, are still valuable at any level.