We expect the most common usage of the OpenMRS Reference Application to feature shared computers at fixed locations around the hospital, e.g. there would be a fixed computer in a consultation room, rather than having each user carry around their own laptop/mobile computer.
Therefore we expect that in the the most common scenario, you want to log into the same Session Location that was previously logged into from the computer you are using (instead of using the last Session Location selected by that user).
To this end, we store a browser cookie to remember the last selected session location, and select this location by default on the login screen.