IPv6 is actually better for privacy. First, the IPv4 address space is tiny. Say, a PING packet is 84 bytes, so pinging the entire IPv4 address space will take

IPv6 is actually better for privacy. First, the IPv4 address space is tiny. Say, a PING packet is 84 bytes, so pinging the entire IPv4 address space will take you all of 336GB of traffic each way (not even accounting for the reserved parts). That can be done in the space of an hour in a decent connection. So things can and are being trivially found by brute force. If a vulnerability is found in something interesting you can bet that by tomorrow lots of nefarious people figured out who can be broken into. Second, IPv6 has the privacy extensions, which means that even if somebody knows your address today, this has a very limited lifetime to it. Privacy extensions regularly randomize your IP address. Under IPv6 even normal people can get more address space than can be reasonably scanned. This makes it harder to identify machines permanently, makes it harder to figure out how many machines there are and makes brute force scanning extremely impractical.