Now they instead gave the opportunity for other bitcoin holders to do good with the /dev/null'ed coins.
It's like giving up quota in a shared storage system for all others (in proportion to their quotas). And not like e.g. throwing away food or destructing buildings.
But the point is that you can do far more good by sending the money to some of the people who need it most, those in the lowest economic positions.
Rather than effectively sending it to the "average" Bitcoin user, which is definitely not in the lowest economic position -- and whatever the average Bitcoin holder spends on charity, it's only a small percent.
This is why Bill Gates spends his money on the Gates Foundation where it's designed to help those who need it most, rather than lighting all his money on fire so that the deflationary impact will help everyone in proportion to their savings.
By the standard that someone would need it more, vast majority of consumer spending is a lot more wasteful than just burning money.
I don't think it's clear whether the world would have been better or worse off if Gates would have just burned (or preferably /dev/null'ed) all his money.