Wow, I didn't expect this to get this much traction!
Since it did I'd like to refine the suggestion a bit:
Vanity merchant
This merchant comes every weekend with a selection of 6-12 random vanity items that you can buy with loot points.
If you have all the items in that selection, you can wait till next week. If you are waiting for that one item to complete your set and have saved up for it then you will be more inclined to join cubecraft every week to check if the trader has that item you want.
This isn't "OP" since the rate at which we obtain loot points is already stable and this feature is more of a "hey, we noticed you got a duplicate like 3 times, here is something worth your effort". This completely removes the sense of frustration from the duplicate cubelet mechanic since there is still this redemption mechanic behind it that ensures your hours put into the game amounted to a certain progression rather than being lost in the slot machine.
Also, 100% of the 56 votes at this time are all positive, could it be possible to have a bit of feedback from staff?