Larian placed these things throughout the world so it feels lived in. You can only create so many assets with finite time and money, but storage containers, being ubiquitous in any material culture, are a necessity, so you definitely create plenty of those. I can�t ever recall seeing any that I thought in the moment were wildly out of place.
You only think there was too many of them because you went through checking all of them. And again, I caught on before finishing act 1 that there was not going to be anything valuable in these and stopped looking in them once I was no longer worried about having enough camp supplies and lock picks, so I don�t know what to tell you.
There is a logic to the placement of valuable items. Bookshelves in a wizard tower probably contain spell scrolls, the writing desk of a critical NPC probably has some sort of letter or note, barrels often have consumables, armoire�s have clothing, elaborate chests have valuable stuff, etc�
That it took you multiple playthroughs to get wise to the pattern and recognize that crates have rope, lock picks, trap disarm kits, household tools, and not much else in on you.
