We use them lots in Australia/PNG/Pacific/NZ /Indonesia etc. As said by others previously great tool for SA. Great for accurately flying DME arcs, useful for instrument approaches, Locators are low powered NDB's are they not? The RMI on most can be selected to either ADF or RMI hence 2 tools in one me thinks.
What if GPS is for some reason out of commision ie during a War or North Korea manage to take them out with a nasty spy satellite (a bit far fetched I suppose). Maybe some sort of terrorist attack etc. Who knows 911 was afterall a wee bit of a shock to the Yanks was it not; anything is possible.
Just a perspective from down under.
Cheers