While they are certainly more than welcome to make lesser versions of magic items if they so desire, the Headband of Intellect and similar magic items are, RAW, uncommon magic items which actually makes them suited for Tier 1 characters (level 1-4) as printed.
That's fair. I suppose I just don't like the combination of its power, set location, and ease of acquiring. In a typical campaign, you might get a Headband of Intellect at levels 1-4 (likely 4), but it'll be a treasure that you as players can't plan for. It also seems pretty easy to get in BG3; you find some trolls in a house and if you defeat them you get it. It's not at the end of a dungeon or a reward for a difficult quest or anything. All this combined just makes it seem too easy to plan a character around it and then easily acquire the item imo.