The problem is that - to me - the rewards don't feel *deserved*. If you're lucky enough to click in the right place, you get something awesome. If not, you don't. I'd far rather see the situation where you're able to deduce the location by talking to people, which isn't the case for many of them. It's just a bit too random for my liking. If nothing else, at *least* give an indication that there's something worth finding. Why would a magical ring end up in a random barrel on the street anyway? It doesn't really make much sense without a backstory, and objects appearing in nonsensical locations - for me - does take me out of immersion a little.
I think a good example of something similar that I *don't* have a problem with comes from Ultima VII and the Hoe of Destruction. Locked in a shed, with a nearby NPC who gives you the backstory of the weapon. He tells you that he lost the key on the shores of the lake, said shores being covered with assorted junk. In this situation, it's a similar objective - find the obscure object by clicking in the right location to get a major reward - but it's goal-based; you know there's a reward to be found out there, you're given a (large but not insurmountable) area to search for it, and you're welcome to choose whether to investigate or not. The game has been honest about the choice available to the player.
I have a very similar rant about many Flash room escape games, actually, although in *those* situations the random clicking is actually necessary for completion, which is significantly worse! Too many people conflate obscurity with challenge.