I saw this post in the IFFG that I totally agree with:
This would be really fun to have. It could get you discovering new areas of the world, airports, etc.
It would spawn you in at a random airport, and you’d have a FPL to another random airport.
It could supply you with adequate fuel, pax, cargo, etc.
You can either select the plane or it would be randomly generated as well. But if it was randomly generated, it would give you a plane suitable for the route. (It wouldn’t give you a 787 for LHR-BHX, or a Cessna for OMDB-YPPH.)