When I go to my messages and click the “new message” button, focus is automatically placed in the “subject” field. This means that to set the recipient, I have to backtrack with shifttab or the mouse.
The alternative might be to move the recipients below the subject, but I think that’d be worse – it’s antithetical to the way every other messaging system works. 
In this specific case (compared with clicking the Message button on a user’s card which indicates you want to talk to that person) that makes sense – the message is open ended, it could be to “anyone”.
Yep, that’s exactly right. I’m using private messaging a fair bit at present to help get things organised and sorted on our new forums, so I’m doing it from my personal messages hub, rather than off the back of posts etc.
Sure @eviltrout perhaps you can take a look, this might be easy. Conditional focus based on how the message was initiated. The odds that you want to talk to yourself… are low. Usually.
Specifically any time “yourself” would be the message target, focus the to: field instead. Not on touch though I guess because that will pop keyboard.
This wasn’t too hard to change:
https://github.com/discourse/discourse/commit/c28dd826fec5ba6963cd0dc64e1efb745079a5dd