Jim,
Yeah, well, that's the whole thing. "It should". Android life has changed for the worse with MPT and the loss of usb mass storage mode. And either enabling/disabling USB debugging on the device all the time is a hassle and not all the household members get it.
You've seen my other requests for features to help in that area. Short of that, I've had to resort to virtual devices coupled with other file sync tools.
And as I mentioned, we've got a lot of different memory devices used as music storage for cars, audio systems: usb sticks, Sd cards etc. they are managed well as devices, but need to be setup first.
For the case where the devices are auto-detected properly as you note, I'd settle for a "Manage Devices..." option, since (even if detected) they've got to go there to setup and configure anyway.
Anyway, I thought the 'Add XXXX...' was a small and intuitive addition, and would make the left side bar a little more consistent. "Add Playlist..." under Playlists while we're at it.
Right Click operations tend to be less intuitive and the option of last resort for most of the common users.