It is preserving the sum of knowledge being generated on the internet, which is orders of magnitude faster than any other information and data generation system ever in history. It is extremely important to keep records of everything we do online. Saving a life now is great and all, but documenting history like the archive does is essential for history to be preserved.

Also, to generate revenue they would have to privatize some of their data or start selling ads, which for the same reasons wikipedia is funded by donations, doesn't work with public services.