So, this might fit more with the planned (someday) mesh deformation tools, but:
What if the Transform tool in Vertex mode could act like a spherical brush almost, making the specified changes to vertices within the sphere, but also with a falloff (so, the default normal-curve falloff would affect vertices close to the middle of the sphere and those at the edge basically not at all).
I’m thinking of it kind of like Blender’s Soft Selection feature, but without needing to select vertices.
You could preview on the mesh which vertices will be manipulated and how much. The radius of the sphere could be adjusted with the second slider that most tools have, but Transform doesn’t.
This, I think, would give a lot of power to the user, and the falloff would help with some of the artifacting seen when using the transform tool and masks (or would eliminate altogether the need for masks in a lot of circumstances). Basically like a transform brush, but performed by placing the transform tool’s pivot instead of brushing.
Here’s a very thrown-together mockup:
