Could there be a tool that selects connected curves that touch each other in a similar way that the selection of chained edges works now?
Reasons that would be good is to debug open curves (or closed but bad ones).
Highlighting end points of curves also works, but if the curve lies on top of another one and has an extra point (so not a duplicate) this might not be as clear - unless there is a different display of end points that lie on top of eachother.