It's a 0 second War Table Quest. You basically just press a button to activate the content. Yes you have to do a quest in the Hinterlands to get the option to have a mount in the first place*, but that is for a story reason, since you need to be able to sustain and care for your mounts (add copious amount of lotion in the Bog Unicorns place) to keep them alive.
If there was an actual quest, with dialog, new areas and combat, the mounts would be far more valuable, at least for me.
*You don't even have to do a quest. You'll just have to talk to Master Dennet. It takes less than 5 minutes to get from the Crossroads to his farm. It takes 0 seconds to complete the War Table quest. You can even select the DLC mount befrore going to Master Dennet and have it standing on the farm when you get there.