The problem with creating custom spacecraft each time is it's expensive and takes a while. It's done to get the most out of a single rocket launch (and because

The problem with creating custom spacecraft each time is it's expensive and takes a while. It's done to get the most out of a single rocket launch (and because it extracts the most money from the customer AKA Congress AKA taxpayers). CubeSats have been revolutionary for standardizing small spacecraft launch. Next I want to see CubeLanders: standardized vehicles that land your payload on the Moon. Also I wish we did more on-orbit spacecraft assembly. A lot of the mass limitations go away if you don't have to fit everything for a moon landing and return onto one superheavy rocket. Just scrap the SLS and pay for a bunch of smaller launches!