In the past it was discussed that Players would someday be able to generate missions. Is that still the intent?

Yes, they really want to allow Players to do that. As Luke was saying before, they build objectives in a simple manner, such as delivery missions where the Player picks up a box, and then drops it off somewhere else, although admittedly it's not that simple behind the scenes. However, it's not one mission but two objectives: pick-up, and drop-off, and they've built those separately. For example, in a mission where you steal a box, the first objective might be to do something first (like kill an NPC), but the end is the "drop-off" part of a delivery mission and they've just stitched those things together. As such, they could allow Players to take their objectives, and hopefully stitch them together into a coherent mission, after which the only thing to do is to decide what is being picked up and dropped off. It's a little like the Service Beacons, where when you're requesting a pickup the game always knows where you are so it's easy to determine what's being picked-up, and where it's going. For the Player-generated missions, they would need to expose all possible locations as an option because the box (or whatever) that's being picked up and dropped off, could be anywhere. This gets particularly interesting when the thing being picked up needs to be dropped off at a location that is secret or hidden, which therefore requires the Player completing the mission to have learned where that location is.