Even if attunement slots aren’t an in-universe thing, the in-universe curse could just be that you can’t get rid of the item. No matter what you do to it, you end up finding it in your possession again shortly thereafter. Doesn’t do anything else but take up space, but that can be bothersome enough on its own.It depends. It is certainly a burden for a player who gets attuned to it. But does it really satisfy you from a lore perspective? First off the scenario requires a world so full of magic items that even an enemy minion has three other magic items they would like to have attuned. Secondly I usually treat attunement slots as a metagame concept that characters aren't really aware of per se.
So in a very magic item heavy campaign setting where attunement slots are an in-world concept I think it makes sense, and is kind of an interesting idea. For most campaigns I wouldn't recommend it.
Cursed magic items are a pain to actually use, since Remove Curse is a rather simple spell to use. I generally try to give cursed items a benefit as well as the curse, forcing players to decide if it's worth using once revealed. Even better if destroyed once uncursed, preventing them from giving it to another player or NPC.I'm a big fan of "but also" when it comes to making cursed items.
For example, a cursed wand of fireballs. It works as described "but also" causes you to lose all of your third-level spell slots while you're attuned. A 5th or 6th level spellcaster might not mind being cursed, depending on circumstance...but around 8th or 9th level, they are going to start looking for a way to get that curse removed.
And if the item in question has some properties that you no longer find desirable--like, say, it gives you a two-way telepathic link to the BBEG, so he always knows where you are--that's additional motivation to get rid of it.Even if attunement slots aren’t an in-universe thing, the in-universe curse could just be that you can’t get rid of the item. No matter what you do to it, you end up finding it in your possession again shortly thereafter. Doesn’t do anything else but take up space, but that can be bothersome enough on its own.