was driving me NUTS as well.. UPDATE for 2024.5:

CMD double click turns on axis lock, turns axis white and now drag anywhere in the viewport to limit to white axis.

regular double click turns axis lock off again.

It’s fucking beautiful!

Getting half way there:

Put the nulls into a Tracer.

Set the Tracer to “connect all objects”. Which will give you a spline with points for each null.

Use a cloner in object mode and use the Tracer as the object driving the clones, and set to “vertex”.

Or use a matrix object.