I can't speak for everyone, but I've spent like 80% of my time building and doing building related activities, and very little time focused on bosses, basically only driven forward so I can unlock new building stuff. So for people like me, H&H is a huge thing even with only what has been revealed so far.
Being able to build and shape your environment is really what sets these sort of games apart from other games. You can pick about any game out there to go fight bosses if that's your thing.