What is the purpose for nuclear waste?

Nuclear waste is an unfortunate by-product of the process of nuclear fission for the purpose of energy production. The spent fuel rods are "safely" stored and sequestered, but will remain dangerous for thousands of years.

As far as I know, there is no "purpose" for nuclear waste, other than to convince people that they do not want a power plant in their backyard. The theoretically possible process of nuclear fusion (which is how the sun works) would produce less radioactive material and waste.