You still have to make the grind worth the effort. To keep subs up, the grind is made intentionally long. If it were only 1 or 2 per item, the grind would need to be substantially shorter and less difficult, which in turn would lower prolonged subscriptions because many powergamers quit once they reach a level they deem "the top-most end."
Making the items less useful and keeping them very difficult to acquire would also lower subscriptions, because those that normally would grind for them will deem the game "too grindy" for negligible benefit.
In essence, the items and bonuses themselves are not the problem, and a 35% gap between the "haves" and "have-nots" makes the grind worth grinding. Making it less would make it pointless.
In other words, just leave them alone.