Speed. I sometimes try it with my IMAP server (dovecot, around 15GB of email) and it's blazing fast to browse the folders.
It also is quite a light feather (~20 MB of memory).
Claws-email is another very fast and very light email client.
Started programming at 12, didn't stop until now and I like it more and more (getting close to 40).
The author seems to jump to generalizations. For example, from "I can’t find the enthusiasm to program anymore" he goes on to "we try to discover new sources of inspiration". Who's this "we" he's talking about?