"Would only talk" is only remotely interesting if the character in question is, in fact, possessed of anything interesting to say. Ryuk is not. Ryuk set up the entirety of Death Note because he was bored and mostly just sat and watched. And even if he said soemthing someone might want to respond to, the entire concept of DN shinigami is that you cannot interact with them in basically any way.

In other words, he's no better than just tossing OOC posts IC and hoping someone wants to do something with them.