What is the point of destroying stalactites and stalagmites in The Witcher 3: Wild Hunt?

Having done a complete playthrough including the two DLCs and every single quest (tracked with a checklist) + fully exploring the world including the most mundane of ruins and locked huts (tracked with a map site), I can safely say that there's not much of a reason to destroy them whenever you see them, other than if you see them blocking the very occasional chest. They don't drop anything or grant rewards per se.

My guess is that when they implemented Aard-ing boulders/walls/crates/barrels/doors to get passage, they decided they may as well do it for those rock formations as well, but in the end they didn't really incorporate the feature into the game's design.