This is true for the most part. Personally, I thought KF was really, really boring compared to Vault and Crota. But rewards are a big part of why I hated it. There's no way to know if it would be more fun with better rewards, because that isn't what we got. Vault had the best rewards by far. Crota had the second best rewards, and KF had complete trash. Since that is also the order of best raid to worst raid, you might be on to something. But there isn't any way to know unless bungie upgrades the rewards for all the raids.