Maybe as an experiment to make boundaries that are important to visual pilots, easily identifyable landmarks, instead of some randomly defined point or line on the map? Or maybe as an easy prompter for London Info (who is not radar equipped, as far as I know) to know when and where to let an aircraft freecall Farnborough?
If I were to plan a flight through there (not likely in the near future, but maybe coming spring/summer) I would pick one of those points that define the LARS as one of my turning points, and plan to switch to Farnborough there.