Imagine being part of a development team responsible for making DLC fluff like mounts and outfits. Now imagine knowing that whatever profits you receive from this fuels further DLC (and thus, your job).

Now imagine meeting with your coworkers and coming up with a cool idea that should sell pretty well because of timeliness of it! Hey, there's an event that features Spriggans! Surely a Spriggan mount will sell if we can have it ready in time to sell!

Now imagine upon releasing your hard work, with high hopes to be immediately shat upon by people who think it's not good enough to pay for...but so good they'll throw a fit about not being able to get it for free.

The DLC team makes DLC. I see what they did as good business decision. If you made a DLC mount with potential for a good sell, why wouldn't you sell it at the optimal time And why shouldn't they be trying to get as much cash back in for their work? They're not the main dev team.