I like GOTW, I just don't always have the patience to replay every move over and over again till I find the best string of moves.
GOTW is like chess puzzles. Chess puzzles won't make you a better player, and are usually made up of unrealistic situations, but can still be fun to those who choose to play them, although they still won't make u too much of a better tourney chess player.
But, GOTW can teach you a lot of things about the game, primarily how to make the most of every turn. Since on MP, you don't have the luxary of knowing the map, it may not always help, but GOTW has taught me that you can do so many more things in a turn than just your tired old strategies. It can teach you new techiniques to getting places faster, to be more efficent, and how to kill everyone really fast in 10 different ways.
of course, this is against the AI, which doesn't really attack you, so it may not be helpful agianst rushers. But the Deity AI has a Great Leader, a Barracks, and Iron Working and Bronze working from the first turn of the game, so they do defend better than any human will (except in the first 8 turns or so).
It does take skill to post those early BC Deity victories, and anyone who doesn't agree, should try to get the top spot. Yes, if you are good enough at the game, you'll probably crack the top 10, but some of these GOTW guys can really shred a map early in the week, and leave even the best of MP players scratching their heads.