New addresses can be generated without generating new private keys.

Monero, for example, has no address reuse at all in the blockchain-- it's required for the prevention of double spending there. It seems to do okay with it.  The original bitcoin software never addresses w/ pay-to-ip; and even with addresses in use it the practice of reusing is somewhat inexplicable from a technology standpoint: it _really_ screws up your privacy along with that of people you transact with, and you can't reliably tell which of the payments you had outstanding were confirmed.... I think if it had been realized that people would behave the way they do, it likely would have been prohibited in the Bitcoin system from the start.