Is it all that useful for regular desktop mail client? I can understand it's huge usefulness in browser or on mobile but on the desktop? Yes, it simplifies mail management, but (clunky) IMAP is already and works just fine?
> but (clunky) IMAP is already and works just fine
Well, 'works just fine' is not what I would say about IMAP, more like 'works most of the time'. But in the end, IMAP is just for accessing mailbox and mail. JMAP also covers (besides server side actions and settings) calendar and contacts. If you remember, there are a separate protocols for these now (CalDAV, CardDAV) which are totally unrelated to IMAP. A desktop client with a full JMAP support would be close by the functionality to Outlook connected to Exchange, which is a thing many desire, especially in corporate settings.
I'm aware and use those protocols. What's the benefit of bundling IMAP/SMTP/Cal|CardDAV into single JAMP protocol here? Those separate protocols work great and if someone only needs mail can only use IMAP/SMTP?