There are only two rational reasons for bases on the moon:

1) We decide to go full speed ahead on solar power satellites and lunar resources will save enough money over lifting them from earth to pay for itself eventually (solar power satellites are only marginally rational today, but political or economic changes may make them more so), or

2) We decide it is worth the cost as an insurance policy, http://www.sylviaengdahl.com/space.htm , especially http://www.sylviaengdahl.com/space/survival.htm