Can you describe how this works? According to my googling this will automatically smooth lines when you draw them.
We do have line tool, and you can hold alt while drawing a line to snap it to an axis. Otherwise it will draw a straight line for you. If you want this other tool you may have to describe it for me.
Edit: so you want this Seems cool, but only applies to the 1px brush. This is a problem I've had with that brush in the past, but it's understandable why it does that.