Actually they did prove people who claim this wrong. They don't display all icons but rather a single page of icons with 2 pages for weapons and armor..... and 1 page for general. From the looks of it and how the other systems work (exotic collection/shaders/etc) they completely revamped the entire vault/save system. Which I am sure took a lot longer to do. So bungie gave more vault space with their current system and then truly revamped for TTK.