I would like to see OpenHome support in JRiver too, mostly because it just works well.
The points AndrewFG raises are interesting, I did not know most of that, and it's true, the 'right' way to go sounds like it would be DLNA v2.0 if that indeed does do playlists.
However, I don't know any devices that implement this? OpenHome is gaining some traction - it is used in Linn's DS players (obviously), but also in a handful of other niche hardware players, and there are now also good software solutions (a Java-based player, an interface to MPD).
Out of all the solutions to this problem, OpenHome seems to the most widely supported and it is available for anyone to implement.
Many companies seem to have developed their own solutions: Naim players do on-device playlists I think (no idea how, must be something proprietary), Sonos does (again, proprietary). However, is there any device or software program that has implemented the current 'right' way to do it of pushing and pulling playlists as described? I don't know of any.
Adding OpenHome to JRiver is also rather unintrusive - if talking to an OpenHome device, those interfaces would be used, if a regular DLNA device, it would fall back to feeding tracks one-by-one as usual.
It seems like the thrust of opposition to this would be that it might encourage manufacturers to implement OpenHome (at the expense of DLNA v2.0).