It's not just about introverted people with less emotions. There are people who have more emotions that would rather deal with it through text e.g. because they can't stop themselves from shedding tears even though they know it doesn't really matter, and would like to save themselves from the awkwardness.

> people running companies should use an approach that works for the lowest common denominator.

No. They should use the best approach for that particular person. If they don't know what that is then IMO a respectful e-mail is the best way.