In addition to the reasons you stated:

- Bring-your-own domain name with lots of useful features for aliases and routing messages around based on that

- Real human customer service, and with agents that actually want to help you to boot

- Everything follows common standards (IMAP, CalDAV, CardDAV), no need to deal with Google/Apple-specific weird stuff

- Masked email

- 60 GB storage per seat

- Actually usable and good web UI