When I used to work in security, I used Whois every day. In many cases it was to notify a domain owner that their domain had been compromised and was being used for spam. I also used it a lot to track down bad actors because most of them are dumb and don’t hide their Whois.
That's where WHOIS protection comes in handy. If you don't want to get even more spam (the imprint has to be clear text, no obfuscation so gets spammed a lot) but a website that could target Germans (or you're in Germany), you'll quickly get costly letters from specialised lawyers. Having Whois protection usually helps, they tend to give up if they can't get your address easily.
