I have been advocating for Denmark to do the same for 15+ years. The fact that your social security number can be used for anything on it's own is a disaster. Mostly it can't anymore, because you have to do electronic signing with MitID, but it's still considered secret. If you own a home in Denmark, address information is already public, but a little hard to lookup.

The problem with this leak mostly going to be those with hidden addresses or secret phone numbers. Last time something similar happened was when it was shown that you could pretty much just guess a persons social CPR number if you had their birthday. Normally you could narrow it down to 6 or 8 possible numbers then use the phone companies websites, pretend to create a new account, enter the CPR number and check if you guessed correctly. Because the demo was done with politicians, then phone companies no longer ask for CPR upfront.