[dartharva]

Honest question, what do you even need a native client for? What can you do on Thunderbird that you can't on a browser?

[t0bia_s]

If you use multiple email accounts on different platforms (private providers), client is only way how to manage it effectively. Same for calendars and contacts. You probably wont use web browser for edit contact on phone as well.

[dolmen]

Store e-mails offline.