A vampire lord outfit in skyrim had a cape.
Are cloaks lore friendly? I don't recall there being cloaks in any TES game before...
Well, there WERE capes present in the Official Gameplay Trailer, shown in the below screenshots:
http://imgur.com/kC9lUZs
http://imgur.com/ySFsX2A
They're also at 2:26 and 9:00 in the actual YouTube video if you are interested:https://www.youtube.com/watch?v=YlEipFtHw7o
So it's not like ZoS disregarded it, they perhaps implemented it at first but got feedback that players didn't like it, or the capes were too faulty or may even be planned to come out in future content. I would say not to ignore the capes for the time being and wait for/if a ZoS employee talks about it in the future.