It's kind of a both sides of the coin issue I guess. You might have a non-DLNA server, or you might have non-DLNA clients (there are lots of them.) Pulling the data as files via the network is sort of the simplest, most ubiquitous scheme, so any player should probably support it. Nothing wrong with supporting other options, but don't skip the one that basically anyone ripping media to a server can support out of the box basically, however they are doing it.

And of course there's the issue of the automation system. In order to integrate media into an automation system, the AS has to understand how to read in the data about the media available, present it to the user, and then has to know how to send a command to the player to play it.

If the player/server only supports DLNA, then the AS system also has to support DLNA, which probably not a lot do. Whereas lots of systems can pull in the info from iTunes, DVD Profiler, My Movies, J.River, etc... and or their own media manager, all of which generally just provide the shared path to the media files. So that path is all that the automation system has available to send to the media player to get the media player to play it. In that case you need a player that can be pointed at a shared file or directory.