Pokémon is a good example. There is no item in the trash cans throughout the whole game (the originals). I and many others do check every trash can ever. And the reason is managing motivation. The game teaches you that there might be something of value and that is a heavy hitter on your dopamine. Directing the motivation towards disappointment is the essence of bad game design.

It is good design only if it’s good. The prevalence of Indy games in modern gaming culture has taught me that games should stick to what they do well. If exploration is a meaningful and engaging element it can be excellent. Most of the time in RPGs it’s a drag. And even if you don’t like it, the influence on the parts of the game that are good means you can’t skip it. In an RPG, collectables is something I never interact with because it’s boring. I am however getting every usable item there is even though I don’t enjoy doing so.

I would even argue that this practice of spreading items in lesser important places is often bad design. It motivates a player to do things that are not fun. Why should this be in the game?

As a bonus it is easier to balance a game when the amount of items does not vary that much.