The way I look at is there's a limited amount of DLC they could possibly put out for this game (there's only so many Beatles songs) and it is guaranteed to be great (hey, it's the Beatles!) so there is no reason for me not to get every piece of DLC for this game.
And the fact that there is going to be an unique dreamscape for each DLC song (when necessary) is an instant sell for me!
To me, the game will feel incomplete without all the songs at my disposal. Who else is with me?