They were offered as add-ons in the GBs over the past year or so for folks with vintage Cherry, these new Korean boards, and Phantom. More and more people are getting their hands on the Korean boards and now with LZ-GH, Phantom R2 and cases like Skeldon-GH there will be even more people needing 1.5 mods. I think that is why they become so popular in recent times. As a Model M fan myself, I do like the bigger mods and I especially like the 86-key 1.5-1-1.5 variant. It's the best of both worlds.