I got Fifa'd today. MS has known about this problem for several months and failed to secure their system. Now my account is locked, my points are gone, and I had to cancel my cc.
I guess for $7 it's worth trying, but this is one of those games that I played for some time and ended up wishing I hadn't. Especially as a big fan of the Metroid series.
Probably not worth $3.50 unless you play L4D2 a lot. The map itself sort of sucks (and is only 3 chapters), and the mutations are pretty meh at this point.
I'm willing to bet that they sell a shitload of DLC at full price because people buying the game on sale justify the savings as a reason to buy the DLC. So while I agree with you, MS probably does this on purpose to sell more overpriced DLC.