As a DM I look at the campaign I am running. I hand pick magic items that make sense in my dungeon. There is also the feat of why have magic items in a hoard. I believe, if I am a hobgoblin warlord and I have magic items, they will be used by myself and my legion during the battle with the player characters. Healing potions will be drunk, scrolls will be used, magic armor will be worn, and magic weapons will be used against the players. Having magic lay in a treasure room makes zero sense. In this manner, player characters have earned the piece of armor, weapon, wand or whatever it is.
Second, is that magic items don't need to look magical. I have found that a player character will take the ornamental sword that looks pretty but is useless in battle rather than a sword that looks battle used and worn but is a +1. Unless they have detect magic and identify handy, they grab what they can before reinforcements or something else comes along. Carrying capacity limits how much they can take with them and the time doesnt have to be unlimited to choose. Most magic items in my campaign are overlooked and left behind.
This is just how I use the magic in my campaign. It gives the players the ability to find and use a great magic item, but also limits their ability to access the said item. Current campaign, I have 6 players, each player has one permanent item, with three of them having two. They have one scroll and five potions as party magic items. It hasn't offset the balance of the game as a +1 anything doesn't really help when you have 15 Bugbears using military tatics or 3 cockatrice attacking from the shadows.