Nepal needs to do and change many things when it comes to earthquake preparedness. They aren't a very wealthy nation so many plans probably weren't made because of finances. Thankfully they are getting a lot of help from other nations right now so hopefully they can use those funds for many things including a good map.
Since earthquakes can follow geological patterns, I believe that a map of the recent Nepal Earthquake could be helpful in preparing for future earthquakes. This could also bring insight to the rebuilding process. Certain areas may be more sensitive or more prone to earthquake activity. Any knowledge that can help in the face of potential future disaster should be sought.
It is a nearly impossible thing to be prepared for. They are totally out of nowhere and could happen at different magnitudes anywhere so its almost impossible to prep for the amount of damage. Things like Nepal can show the degree of which to prepare though so it should help for the future.
A map will not help. This is because earthquakes do not always have the same types of paths or patterns as previous ones did. They are all independent of each other. What would be better is for everyone to have a preparedness plan in at least the fault-line zones of the world.