Just because certain container types (like skeletons and barrels) are unlikely to contain decent loot, it does not mean that it is not worth checking them.
It does. Since it's simply not worth the time to check when you have so many resources easily available. There's literally an overabundance of stuff where you can be swimming in gold and resources with nothing to use them on. So checking a barrel for the 0.1% chance it contains your 169th Thieves Tool you'll literally never use is pointless.
The awesome Smuggler's Ring is on a random unmarked skeleton you can find very early. Since there is a 0.05% chance a skeleton can "drop" a goodie, you will check all of them, especially on a first run. There is a major difference between a container type never or rarely having good stuff. It is just a nasty trick to bloat gameplay times.
It's not a "Random unmarked skeleton" it's that specific unmarked skeleton.
Which is the thing. Yes, on your first run, you'll run around looting everything. But after that you should know which unmarked skeletons have the actual items on them and can ignore the other 99.99% of them that contain nothing.
Every worthwhile item is in a static location. The only thing you can find in randomized containers are resources (Camp supplies, Thieves Tools, Disarm Kits, Scrolls and low tier Poisons/Oils)
Except for the Caustic Band, all the others on your list are lost if you fail to pick them up before Act 3.
And literally none of them come from a container.
You talk about time spent opening containers and not finding good loot... Which is because there isn't good loot in random containers. Heck, even the static containers there's pretty much just the Smuggler's Ring as the sole worthwhile item and maybe the Lover's Rings (Other than that the items I can recall off-hand from skeletons are just bad. Like the ring that gives Momentum if you're at less than 50% health, the hat that gives +1 Wis Saves or the ring that gives +1 Deception)
