Given their repeated botched rescues, should the US military leave such tasks to the professionals?

The Mossad are the most 'elite' force there is by far. You can plan for the greatest Rescue Mission possible, but other unexpected factors come into to play when it is attempted. It wouldn't surprise me if some of these missions are already known before they even take place. You already know it is going to happen, so it is not a real surprise, you just really don't know when.