These are empirical psychological conjectures. My own experience leads me to believe that they are, in general, false. Perhaps there are individuals for whom they are true; perhaps you are one of them; but they are not universally true.
I don't think you understand.
It is empirically and universally true that our desires do not change the makeup or organization of the world around us.
It is also true that a character's desires change the makeup of the world of 4e in that they desire an item, and find it in a treasure hoard.
This not given an explanation or a justification. It is simply how the game mechanic works. Thus, this is a mechanic that is largely impossible to play in-character, because the character cannot control that aspect of the world, because people do not control that aspect of their world, and there is no reason stated that your character could control this aspect of their world.
(I suppose it's possible to posit a narrativistic universe a la Pratchett where narrative needs do define physical reality, but that's certainly not the explicitly stated reality in 4e, and is kind of a joke in Discworld, so...; and, come to think of it, it sounds like something the Signers in Planescape would be fans of, even capable of, but that's also a specific setting's tropes.)
This isn't a statement of ability or intuition, of qualities or competencies, merely of fact: wanting something doesn't normally create it, so your character's wants cannot normally create an item, yet your character's wants habitually make items appear with the wishlist mechanic. It breaks with reality without explanation.
For some people, this kind of thing will be counter to the experience they're looking for. For others, it will not -- it may even be in line with it (it is narrativistically appropriate, since protagonists do tend to find what they're looking for right at the right moment). For others, it might be, but they're fine with it for little bits like this. For others, combined with other things, it will be enough to break the experience.
Under typical circumstances, you
cannot conceive of this mechanic in-character, because people can't
do that. It doesn't matter how "good" at this you are, it's not something that is possible in-character because it is not something that is able to be done in-character.
Early 4e leaned perhaps a little too hard on mechanics like this, and the totality of them certainly scared away many people that it didn't have to.