Having both add obstacle, and solid detection would be awesome. In fact I think both would used together quite a lot.
One of the most asked questions on the forum is how to do multiple instance pathfinding.
This would work quite well in conjunction.
I guess the next question would be would something like Add Waypoint like how Moveto works be worth doing?
I'm kind of rolling that over in my head an I don't think it would, because if it were pathfinding, you wouldn't want each to find a path. You would use a single objects path, and "flock" to that object.