It's a bad seed if you don't enjoy playing on it. If Bonemass is behind a plains biome and that creates an amazing adventure you enjoy with challenges you enjoy to overcome then it's a great seed. Exploring more to find a better way to Bonemass is part of the adventure. If you think that's just all crap and wtf I'd grab some gear and resources and start with the old character on a new seed. But stuff like that is part of the game, so the new seed might have something similar or something else that feels off to you.