What are important uses of the "Net Tie" concept?
Net ties are an extremely useful concept, if used wisely. If you are part of a team where there is dedicated PCB layout resource (or you have outsourced), the use of net-ties offer additional clarity with regards to the circuit designers' intent. 

They are useful for kelvin connections as you have shown (be it sense resistors or 2-wire RTD converting into a 4-wire). They are useful if you want to constrain the layout with regards to where a node might be physically taken (ie. distance constraint). Likewise their use when netnames may be merged is valuable. AGND tied to DGND at a starpoint for instance. if there is a branch in a digital clock signal where the resultant lengths are different (requiring separate signal integrity considerations)  

It offers the layout and schematic engineer additional flexibility in defining what their physical intent is. It doesn't result in only one solution, it is one tool presented by the eCAD software (constraints being another). 

Your example of the sense taps is a classic example and I personally would have created a separate footprint for that part to ensure the 4-wire variant had the taps exactly where I would want them - between the pads