Come on, your neglect of banner options is getting silly. This event would have been the perfect opportunity to add Scourge, possibly Forsaken, and Draenei banners to the game. Another miss.
Between all the customization items that exist in the game, banners should be among the easiest to make. Less so than sprays and portraits, sure, but much more so than mounts or skins.
They don’t seem to have a problem with regularly adding themed mounts to go along with new skins. But themed banners to go along with those skins+mounts does seem to be an issue. It’s like they’ve forgotten banners exist. Either that or they incorrectly assume everyone playing this game is a big esports fan and they only ever use esports team banners.