I think it is at least partly because Stoicism is riding on the coat tails on the one hand of CBT and as a way of distancing oneself from negative feelings, and on the other hand of traditional masculinity which has seen a rise in popularity in the face of an out of control social justice / political correctness movement which likes to demonize (especially white) maleness. Stoicism also has better name recognition.
I think Epicureanism suffers from a lack of name recognition, as well as a skewed understanding of what it is about. A hedonistic pursuit of the good life does not strongly invite people who are interested in philosophy. And pleasure seekers may not be all that interested in philosophy.
So I think we should try to reach out more broadly and let people, especially in non-religious communities, know what Epicurean Philosophy is about.