Nearly half of those 50+ were made by one person. There are less than a dozen creators. This is partly because the mission system is very different from SS08, and many users —including one CMM—find the editor too intimidating to even attempt missions.
This situation will improve over time.
Another factor that inhibits potential creators is the frustration of trying to get some ships to behave as expected in their missions.
Many users apparently confine themselves to free roam and MP, and don’t bother with missions.
