Even Roan had to admit it interested him. He saw just how good Rank Three Divine Stones were back when he helped Kihin. Naturally, he wanted to have more of it. It didn't matter how many Rank Two Divine Stones one had. It couldn't compare to the cultivation speed one would get with a Rank Three alone.
Rean tried to sell his weapons for Rank Three Divine Stones. Unfortunately, not a single person wanted to pay using those stones. That's how important the Core Sector disciples and elders thought those stones to be.