So I was looking at a discussion (The Crafting Thread; posted in these forums) about crafting and one of the issues was bag space. In the discussion someone brought up using your mount for bag space. It is known that you can increase their bag space if you go that route (instead of increasing speed or stamina). The question is will you be able to own multiple horses and be able to call on them at any time? If so, I'd wager most people would opt into having one horse as their travel mount (putting points into speed and stamina) and possibly many more for carrying their burdens (all points into bag space for mainly carrying crafting supplies).
"Hopefully ZOS will steal creatively copy the brilliant and widely lauded system of crafting material storage that was used in Guild Wars 2."
Quote by Incendio stolen from said thread/discussion. My input on this is maybe they already have implemented such a storage through your 'beasts of burden'. That is, of course, if you are able to own multiple mounts for said purpose.
Anyone able to confirm or refute this information?