I don't think promises like this should be considered news. Take a look at the list of people who have signed Gates' own Giving Pledge and ask yourself if making the pledge changed their behavior at all: https://en.wikipedia.org/wiki/The_Giving_Pledge.
Historically, it's pretty typical that rich people don't give their money away until their death, and the Pledge itself is not a statement of intent to give the money away during their life.
Giving during your lifetime is a much, much better way of ensuring that it does what you want. It is very hard to control things from the grave, as someone administers it and can do what they want, as long as they follow the letter.
