While true, this has been in place at Blizzard for at least 13 years. Blizzard was one of the leaders on this, not a new convert and it has nothing to do with Microsoft.
I agree it undermines consumer rights, and is important to discuss, but this is not a new change. People really don’t pay attention to what they agree to. We don’t own our Battlenet account, games, items, or anything else. And we don’t have the right to sue them generally speaking depending on country.
Most of the threats I see for legal action are people who got banned for breaking the rules and policies they agreed to. Polices that say their revokeable license will be revoked for breaking the rules and that they are not owed any compensation for that.
The other big real thing that all companies are responsible for is protecting our personal data (real names, addresses, financial information, etc.) Failure to follow privacy rules or failure to disclose a breach in a timely way that conforms with laws, an result in a major legal liability. Blizz has always been good about that, but other companies like Sony Playstation have been deal huge losses in court.