As usual, I wish I had some of these comments before I wrote mine! Just a few reactions.
Yes, the Macdonald's case is more complicated, but no one made a convincing case that the customer could not have tasted the coffee first to determine how hot it was. Macdonald's criteria in serving hot coffee are not the real issue if it were easy for customers to check the nature of the product they consume. That surely was true in this case.
One can separate, at least to some extent, who gets punitive damages from who gets the compensatory damages. But one also wants to give victims sufficiently strong incentives to sue.
I generally do support allowing customers and providers of medical care, other services, or goods, to reach contracts ahead of time about rights to sue, compulsory arbitration, and so forth. Still, the same considerations that justify lawsuits-lies, withholding relevant information, and terrible service- would also be relevant in interpreting such contracts.