Same. I think they came out twice in 2018 - once in March then again in December. They may have lasted until January. I'm not sure if they came out a third time or not, but whenever they've been in the store, I'm either horribly ill or on a hiatus from the game, and can't buy as many crates as I normally would. I'd love another shot at them, especially with Endeavors coming, and the ability to cash gems for Radiant mounts.
That red/black edgelord mount is super popular with vampire characters, I've seen. So I bet a lot of people want them back solely because the shadow-rider senche would be less of an outright gamble.
"I haven't really played much yet, but lemme tell you all about how the game should include X and be a lot more like Y!" - Half the posters on this forum.
"I've been here for years, and lemme tell you all about how they should never change or evolve Z, because then the game would be ruined forever." - The other half of posters on this forum.