How often are you going to utilize the full 19 seats? Maybe short sectors yes but how about those long haul runs.
Comparing it to a King Air in this case, how often could you take a full ship (11 pax + bags) 600nm - simple, never.
As for the Jetstream one would think perfect if you have 11+ pax + bags.
Perhaps there is logic behind it - good luck to them. More flying for us!