Mass & gravity are still way easier to understand on a fundamental level, especially since everything has a certain amount of mass and thus affects and is affected by gravity. It's a much simpler concept. ("Natural") magnetism is (so far) very material specific and I don't think I've seen a good explanation as to why exactly. Magnets certainly behave very differently than other materials and that causes this mysticism in people when they think about magnets. Given the still ongoing research into magnetism and related things like superconductivity there's certainly a lot still to learn.