Question: Why doesn't NASA or SpaceX use the command module as their lander, instead of having another spacecraft as the lander?
I was playing Kerbal Space Program the other day, and noticed how many people used the command module as their lander. Which is something NASA doesn't do at all.
NASA has another spacecraft that serves as the lander, and another spacecraft as the command module. The lander lands on the Moon, and the command module orbits around. After the astronauts are done collecting samples on the Moon, they rendezvous with the command module and return back to Earth.
But what if NASA had instead of adding an extra spacecraft, they used the command module as both a lander and the command module. So instead of having two spacecraft, you can have the command module land on the Moon, and then blast off back to Earth.
Is there something wrong with my thinking, because I'm sure NASA would've thought of this idea a long time ago.