Must say, I'm not a fan of yours or similar services, or whois databases for that matter. Privacy should be easier on the internet for people owning domain names.
Privately registered eu domains are quite nice. I couldn't even find two of such that I own in your database and whois only reveals email (which I made sure from the beginning to be of the same domain that I just registered, so that's useless for anything). People can probably pay for more info though.
Way too many weird people out there.
This is why I lie in my whois data, to the horror of the goody two-shoes on HN I'm sure.
The whois data is a great place to start a social engineering hack. The address or any past address is often used for identity.
Also your question may apply to the other end too. Shouldn't it be easy for an owner of the server to find out who is behind an IP address that is connecting to his server - and I mean easy access to his/her phone number, home address and a complete history of those, too?
It's easy to concot legal, technical and content reasons why this should be.
But perhaps there should be a possibility to remain anonymous (and the browser informing the user that this is the case).
Making it available to everybody just sheds light on the problem, it doesn't create the problem.