"Microsoft is in a position to do this sort of thing easily with Live, but they don't, and they didn't"
What sort of thing? Cross platform play? They've supported that (but for almost every type of game it sucks) and also giving the free extra copy is something Valve do, it doesn't really have anything to do with Sony...
Valve made a DLC for Left4Dead2, released for 360 and Mac/PC. Valve released for free on PC, but MSFT told them they must charge for it on 360, $7.99 (or thereabouts). In response, Valve had a sale on Mac/PC where all of L4D2 was $6.99, and then you get the new DLC for free.
They did, actually. Just not very well. Only a few games had that cross-play (Lost Planet and Shadowrun are the only one that come to mind) and there doesn't seem to be very much incentive to implement it further. I would hope a positive response from this would make Microsoft reconsider their halfhearted attempt.
Me, I'm excited for this increases the chances of me getting one of my friends to actually play a multiplayer game in the same room. Hurrah!
This would mean you can continue your game while travelling.
Microsoft is in a position to do this sort of thing easily with Live, but they don't, and they didn't.