Honestly I don't see why ALL accessories/cosmetics shouldn't default to account-based. But at the same time, it's a free game. They have to make development capitol somewhere. From what I've seen (only been playing for like a week and have no idea about the "real money" items) accessories, hairstyles, etc. that you unlock by using the associated item have three "tiers." Use the item once and it unlocks for that character (I don't know for certain but I believe you might lose access to it if you delete that character), use the same item a second time and it unlocks for other characters (I assume this would mean auxiliaries, and may unlock that item for that character's "slot," so if you delete that character and make another in the same slot that new character will have access to it? I don't know, this second tier is not very well explained at all in the game's UI), and using it for a third time unlocks it for the entire account (no matter how many characters you create on that account). So assuming you can get two more copies of that item you can have it available for every character on your account regardless of how many characters you create (you get three slots for free, you can buy additional slots for AC).
But again, my feeling is it's a cosmetic item, we shouldn't have to buy it three times to get "full access" to it. But then again there are a lot of "expenses" I'm not overly keen on, but it's still overall a much better value than, say, Bungie's "Destiny" microtransactions.