I have a mini skinny from YEARS ago and it's actually very useful when you want to carry your keys and just a card or 2, maybe your driver's license for ID and a few bucks. It tucks away in a pocket or backpack pocket and doesnt' take up space. I use mine whenever we go on bike rides, hiking - anywhere where I don't want to carry the whole wallet but need just a couple of essential things and emergency $$. But it definitely doesn't get regular rotation among my accessories.
My wristlet I carry whenever I travel on a plane since it holds my ticket and passport around my wrist...that way I don't have to pull out my wallet every time I need to show ID at security, the gate, boarding, etc. which can be a hassle when I'm hauling my laptop bag, suitcase, and whatever else.