Perhaps you're playing as a thief or an a stealth mission. You want to know what is being whispered about by two characters far away- or otherwise unapproachable. You affix a crystal to an arrow and fire it in the grass nearby them.
I get it if some people don't like the notion since I'm positing how I personally would choose to use them to listen to the musicians that I hope are in Skyrim. Though it's bullcrap to act like this is some sort of anachronism or implausible violation of fantasy gaming. Palantirs are, heaven forbid, fantasy crystals using magic to broadcast to other Palantirs... And if those post had been called "What About Adding Palantir-like Crystals to Skyrim?", there would likely be much less condescension in the replies...
Oh wait. Maybe it's just be "Keep your Tolkein out of my Elder Scrolls!" variations...
That comes under "shoehorning useless features in". There are better ways to do eavesdropping. Considering that this is not a stealth centric game, eavesdropping is unlikely to be all that useful outside of quests that are designed for it (like the Nocturnal quest in Oblivion). With that in mind I hardly think we can justify working this abstract mechanic into the game. It's also nauseatingly familiar from Fallout, and that is an unwelcome thought at the back of my mind when I'm trying to enjoy my travels in Tamriel again.