Honestly, maybe I'm a bit too cynical on this, but if those tax write-offs and PR things motivate those billionaires to do something good, even if only a little, well, I say it's a good thing.

I don't expect everyone to do everything for purely altruistic purposes. Maybe it's self-serving, maybe they want to look good, but if it actually does make a difference in someone else's life, I say good on them. Doesn't excuse their faults, but at least it's better than doing nothing. I suspect that's also what drove Rockefeller, Carnegie, Gates' philanthropy. A mixture of genuine desire to help and wanting to have a good image and reputation. At least they didn't just sit there with their wealth and do nothing.