This has been my biggest pain point with Intel. Why are sockets changed, seemingly, every generation? There's no point in having a socket in that case. Might as well solder the CPU right to the board.
Sort of the same way in the software world where it's easier to add a new method then it is to enhance an existing method. New methods have no legacy baggage to worry about. Tweak an old one wrong and you run the risk of breaking a bunch of people.
AMD's commitment to forward compatibility is pretty nice, but definitely more work on their part.
Then again, AMD's legacy is making sockets/slots work for their processors :D (That was the whole point of the original athlon)