Personally I think I'd prefer to decouple my email / phone / etc from the ownership of some credential / identifier. To me it's cognitively simple that I have a domain name, and to prove that I control the domain I have to make some change to the domain. When I say (type) it out loud it does feel a bit archaic, but to me it's simple.
It would be convenient if by clicking a validation link or something sent to my email (to prove I controlled the email in the domain) I could verify ownership. But: What about something like AWS Route53. A fairly complicated "enterprise" system for authorization is in place allowing certain team members to make changes to a DNS record in AWS. The people in the organization will change over time, the list of who "owns" a domain might be ever changing. Of course the organization itself might own the domain, but perhaps there isn't a clear single email address to assign ownership to. If the Domain Verification spec required everything to render down to a single email address or phone number or whatever, it feels like it adds potentially complicated questions to how do you distill AWS access down to an email address or phone number? It just feels like the actual service validating the DNS info is potentially taking on a lot of responsibility / complexity with implementation.