Whilst I agree that the Falcon series can be extremely useful for a manned lunar programme, it will always need multiple launches. Now I know that ISS has been constructed successfully with multiple launches, but I would feel safer if the number of launches for a lunar (or beyond) mission were to be minimised. That is why on a separate thread I voted in favour of a Heavy Lift Launch Vehicle.
All that is needed for a moon landing is a single docking in low lunar orbit or EML1/2 to get the crew from the dragon to the lander.
Even with a single launch heavy lift mission you need at least one docking (the ascent stage has to dock with the dragon in LLO on the way back) unless you plan for direct return from the surface of the moon.
So you propose to spend tens of billions of dollars to build a heavy lift launcher to reduce the number of autonomous dockings at the staging point from two
Comparing the assembly of the ISS with thousands of hours of spacewalks with a simple docking of a lander and a dragon that can be done completely autonomously is misleading.
It is interesting that the Chinese are now talking about the preliminary studies for a Heay Lift Changzheng vehicle in the Saturn-5 class of payload capability (again, the papers are on a separate thread in the Forum). Previous discussions had centred around multiple CZ-5 launches, although that might have been simply echoing back western speculations.
It's not surprising that a centrally planned space program that is done mostly for reasons of national presige will come up with the biggest possible launcher. That does not mean that this is the best approach. The russians copied the space shuttle with buran. That does not mean that the space shuttle was the most economical way to go to space.