It's mandated by ICANN.
Probably. It's been a while since I worked in that industry, but ICANN has always been pretty picky about the exact contents of emails.
Changing the user workflow in the way you're describing is out of the question. The entire purpose of clicking a link in the email is to confirm that the email was received at the domain's WHOIS contact address. Allowing a user to log in and click "confirm" without clicking a link in the email wouldn't confirm that.
This is my issue. I've spent years telling clients to not click any links in an email from your bank/insurance etc. but yet Network Solutions and others are still putting a big fat "Click here" button in the email.