I just think this is a perfect example of how stupid some countries are getting... Just like in the UK where you go on a train and every second window has a safety instructions notice, you get told to "mind the step" at every stop, and get told that the aforementioned safety notices are "located throughout this train" every few stops (contrast with central european trains with possibly one small notice per carriage and no special safety notices -- or is it really not that obvious that you shouldn't stay in a burning train, that you shouldn't stay on the tracks etc.) . The fact that McD can get sued for something like this is just fuelling the silly Health and Safety Mania present in the UK (and presumably US). It seems that there is a border between mainland Europe and countries further west, where common sense gets lost.
(If I spilled coffee like this I would accept that I was just a big dumbo and get over it... However some people don't seem to be able to accept that things are THEIR OWN fault, and want to get retribution for someone else's mistakes... I have cut myself badly with a stanley knife, burned myself with a soldering iron, and didn't sue the makers for not including a "Warning, sharp" or "Warning, hot" sign on them -- it was after all MY stupidity that caused this. I could easily find many more examples like this...)
Next you'll have deceased's relatives suing hospitals for having helped bring the person to life, since this was the cause of their death, or at least not warning that life has a high probability of death...