You may be surprised by this but aircraft have had the ability to take off, cruise and land since the very earliest days of flight. Generally you need all three to make a succesful flight. Perhaps you meant it could be done automatically? Well apart from the fact that no commercial aircraft can take off automatically and less than 5% of the worlds runways are equipped for automatic landing, I've yet to see a computer that could make a decision. Sure they can follow a plan, but what happens when that plan changes? Errrr, errrrrmmmm.
The reason computers land jets in fog is because the Captain can't see. Take away any of the numerous 'eyes' of the computers and they can't see either, so who lands it then?