You don't understand direct cause and effect. Your statement is only true if 100% of the playerbase is clearing 100% of the content. Since that's definitely not true for Savage the rewards are not useless because players can definitely use any new rewards towards clearing Savage.
The problem with new content is that it has to have a difficultly in line with the quality of the rewards that it provides without trampling over the previous existing systems that are already in place.
And both of those make a huge difference on whether people participated or not. When people were not doing it at all, it's not actual content that matters. Now that people are doing it, it is.
Hunts are about finding the mob first and foremost not how to kill them. B Ranks being solo friendly now makes it a unique system where players will fly around to search for them and shout out their positions to assist other people. It's no longer part of the massive train that A and S Ranks are. There's no vitriol to B Rank hunting that the rest of hunts have.
