The WoW blog regarding the holiday sale and new Blizzard Shop additions has a lot of information, including a very easy to miss bit of information regarding the Tyrael’s Charger mount and the date that it will be removed from the shop. However, while that information is in the article, it is not in the actual shop page information.
Many players will almost certainly miss the blog in question and thus think this mount will remain in the store for an extended period of time when in fact it will only be there for a mere two weeks. A quick fix for this would be to add the cutoff date in very large and/or bold print on the shop page at or near the top so players are immediately made aware that this is a very limited time promotion and that they need to act quickly if they want the mount before it goes away again.
The more people that know there is a cutoff date just around the corner the more likely you get purchases from them instead of them missing out (and thus you missing out on the profits) because a critical piece of information was missing from the shop page.