It's not. It's just as important. However, this mission is the first to carry an actual ISS Crew. They'll stay on the station and perform science for several months. The Demo2 Mission was pretty much just a final walk through. While being Test Pilots and trained to make observations and a multitude of other functions within Dragon, if necessary, they were, for the most part, just along for the ride.
For the record, I am not an employee of SpaceX and have no affiliation with them. This is just my opinion.