Mans existence in space is dependent on life support and radiation protection.  The Moon has no atmosphere and Mars very little.  Radiation impact on biologics and electronics is immediate.  That impact increases with distance from the Earth, the solar cycle (solar maximum through solar minimum through solar maximum) and Galactic Cosmic Radiation (GCR). We need new technology for radiation protection and that is just one reason to learn what we must from the Moons environment - it is a very big reason considering our planets magnetosphere is in constant change. 

The hurdles we face with going to the Moon are much the same hurdles we'd face in going to Mars or asteroids.  Let's use the Moon and lunar environment to learn what it takes for humans to survive.  Life support and fuel for spacecraft have been well addressed to our current operations.  As we press beyond LEO they will become more demanding.

Solutions lead to overcoming issues..

What would the primary objectives be? I submit:

                                           New technology for radiation mitigation ;          
                                           Electrostatic and regolith mitigation ;
                                           Explore new potential energies ; 
                                           Space Mining ;
                                           Lunar environment platform for asteroids (discovery, tracking, rendezvous,
                                              mining and NEO/PHA countermeasures); 
                                           Biologicand other waste disposal methodologies ;
                                           Dissuade hostile intent ; and
                                           Survival .