It basically says in 200 words what Ubisoft wants you to say in five: "I will not sue you," whether for the busted game or the fact giving away free DLC devalues the season pass you bought. The waiver is buried in the mile of legal text that no one ever reads, but they're required to say they have before they can get their stuff.
This makes it a little more clear why Ubisoft (or any publisher) would do something this. It's not because it's an apology or good PR. As this law firm demonstrates, there's money to be made in class-action lawsuits. Thinning out that potential class can either kill a suit or make filing one pointless.
