The problem isn't simply getting data up there, its dealing with it when it gets there. Aircraft systems are for economic and safety reasons not as fully integrated as many outside the industry might imagine. Landing gear, flaps, thrust reversers, auto-speed brakes and autobrake all require either manual operation or manual arming. There are good airworthiness reasons for this.
Then there's the problem with computing power. The typical desktop computer has a 30 gigabyte hard disk, 2.0 gigahertz processor and at least 256 megabytes of RAM (many belonging to flight simmers have as much as 1 gigabyte of RAM). There isn't that much computing power in the entire aircraft. A really top line latest model FMC would have at most 2 megabytes of memory and use a 486 processor (remember them?) Older 757s and 767 FMCs have only 270 kilobyte memories and are driven by 386 chips - which is why the pilots are continually putting data in manually to check for direct tracks to diversions and so on, as part of their routine flight progress monitoring. For safety and especially for certification reasons, the electronics are kept well away from the cutting edge. Or perhaps you would rather entrust your life to Microsoft XP Professional SP2?
Can anyone seriously expect an ATC controller - who isn't qualified to fly an aircraft - to take over a crippled airliner in unknown technical condition and fly it blind to a safe touch down on the runway? The Helios accident has certainly triggered a rush of bizarre scenarios on this website. Over in Jet Blast we have a crowd of PC Simulator pilots who really believe that it is possible for people who are not trained, skilled and professional airline pilots to recover and land a crippled airliner. Its just a fantasy I'm afraid; the the truth of the matter is that if both pilots die or are totally incapacitated then everyone else on board is going to die as well and there's nothing much anybody inside or outside the aircraft is going to be able to do about it.
Until the day dawns when we have the first airliner certificated for zero crew operation that is...