Well, everything is almost right and wrong, and especially in www you can decide if something is right or wrong, based on user's needs and goals (although this could be a general life approach:)
By the way, keep in mind implementation complexity and time.
But let me give you an example based on your resources.
You have a "company-thing" like Frank Chimero's "Another design studio".
Now, if you can successively assume that mid-age people browsing your website, will be on their job's computer, and also have their lovely email client set up, then ok, you may go with mailto: links!
Mailto links could lead potentially customers be on their controlled environment (native email app), save message for later, continue the conversation as a thread etc.
Btw don't forget implementation.
On the other hand if you have a "startup-thing", the needs and time of a user may be extremely different. He/She wants a fast and easy way to contact you, doesn't care about the address he/she contacting and in general he/she want's things done. This is a kind of user that wants his dopamine served.
So mailto: links may break user's experience.
As a final thought I would totally agree with usability, consistency and affordance issues that are mentioned above. Links on footers are links to pages and mail addresses are used by the user to send emails. If we mix them up, we could end up with serious usability problems.
To end up with it's not that bad using something tried such as mailto link, if and only if there exist a thoughtful reason.
Now If I had to suggest a mailto link or contact page on a developer, I would go with:
"Think of your users and if you have the time, then create a nicely contact section somewhere, else go for a mailto link, and just use a descriptive text".