I would see two benefits of multiplayer aspects:
multiplayer controlled ship:
one captain responsible for commands
one responsible for manoeuvre planning
one responsible for landing dangerous sections
splitting at landing with having maybe different vessels commanded by several players from their own pods
stations docking challenges
plane races to clear a contract first, new contracts on races (best time between checpoints)
shared career: science and money shared, maybe per faction so that you can decide to compete for the most profitable space program.
DMP is a great mod but is missing these features and actually multiplayer is what I am really missing on my side.