@ffngg(View Post) Because implementing it meaningfully in TPT would mean a "magnetic layer" has to be added which only affects metal-y elements. And we have quite a few layers already - particles, newtonian gravity, ambient heat, pressure, X velocity, Y velocity, all are considered in the movement of every single particle.
Magnets aren't really rejected. I'd love to see the cool stuff people could do with realistic magnetic fields. By that I mean magnetic field lines with a + and - side, reactions with existing elements, and all that fancy stuff. I just don't really know how to code that, it is a lot of work anyway.
Edit: The problem is not adding a new field. We already have a lot so clearly it isn't that hard. I just don't want a copy of something we already have that only affects a few elements.