Because it's *fun*. Really, it's that simple. Whilst other games may have breathtaking graphics, or an epic narrative, or some amazingly cool new gameplay feature, LBP is, quite simply, just great fun.

Try sitting down to play it with a couple of mates, and I guarantee you'll be laughing your asses off within minutes and just having a grand old time.

You tried it ?

It's awesome :) .. really clever level design through the whole campaign and a difficulty that really starts showing at some point @_@ .. and in multiplayer it's infinately fun.. this is a game i can bring along if i visit my moms place or something and play with her and both my sisters (and it'll be fun.. no splitting a small screen) and they actually know how to play.. after a little instruction XD

because one of the best rated games of all time is worth hyping

Having played LBP it is pretty decent game, not something I would buy for full price. The COOP is what makes the game if you have friends, always fun when people die.

The reason behind the hype is the fact that the game seems like pure fun. While the games you mentioned don't seem as fun to me.

PS: While I say MGS4 is not fun to play (meaning I don't like the gameplay), it is the story that makes that game (meaning I like the story, somewhat :P).