OK OK this is an interesting idea. Seems you're suggesting a space taxi system. One craft to deliver a payload (detachable crew as @Zhetaan says), the tug to move it to the Mun or wherever, and a lander to bring it to the surface. Do I understand that right?
But I do have a contract in stock with six tourists to the surface of the Mun. This is difficult for me. It basically means I need to land a mk2 lander and a hitchhiker storage facility. Put those two things together and the 1500 delta v required to descent and return from Munar orbit and now I have a tall, awkward craft. And it requires refueling at a mun orbit base. And that's why I'm pursuing infrastructure that allows me to refuel.
Of course I could just make a bigger lander, use drop tanks, launch it from kerbal with big engines and lots of reaction wheels. But my assumption is that the infrastructure, using reusable components and vessels purpose-built for a small part of the journey, is more cost efficient. But @steuben has me wondering if that assumption is correct. Maybe I'm just doing this because I like complexity.