It would be nice if you could crease a single vertex for the subdivision modifier to get sharp points like the corners of a plane or a single point on the mesh.
This is a plane with a single vertex pointing upwards. It gets smoothed out and dull by the subdivision modifier. Also the corners of the plane gets smoothed and rounded.
This is the base mesh. The single point in the base mesh is much higher and sharper than the subdivided mesh.
There should be a option to be able to crease a single vertex to make sharp points possible.