I'd like to thank Harmonix for Rock Band Blitz.
As a member of the US Military, I find myself moving to and fro from station to station, be it TDY or PCS. As much as I love Rock Band, it's hard to deny that the plethora of instruments is quite a hassle to transport. I've had to leave the guitars and drums at home, sadly.
I still followed weekly DLC releases, saying "Ooh! I gotta get that one!", but the list was growing ever longer, and even more daunting. Despite having access to online stores with shipping, the costs for new instruments were downright terrifying.
Then, Rock Band Blitz comes along. It's not the same, of course, but it reminded me of how much I love Rock Band 3, and it's an awful lot of fun. It also allowed me to catch up on Rock Band DLC, which I am sure you are all pleased about.
In short, I love how Rock Band Blitz combines the interactivity with great music with the portability that is invaluable when you live out of two duffel bags and a carry on.