Nitpick about history: the LM was definitely not one of the easiest parts of Apollo. It was the long pole in the schedule for a good while; part of why Apollo 8 was flown as a lunar orbit mission was because the LM wasn't going to be ready for testing in Earth orbit until at least early '69, and NASA wanted to test the CSM beyond LEO anyways.
> the LM was definitely not one of the easiest parts of Apollo
It had to deal with a lot of uncertainties which were unresolvable from a distance. But conceptually and developmentally it was one of the simpler elements. Certainly simpler than keeping humans alive in space or a launch vehicle programme.
Better analogy might be Gemini. One could similarly criticise Gemini (or any of the early Apollos) as being breathtakingly behind the task of landing humans on the Moon and then getting them back alive.
