Well they will have done their research and found that this is a good thing to offer. I can't imagine the noise level would be any more intrusive than a family who are split up and keep wandering around to talk to each other or any other group who keep turning around to talk to one another in a normal set of 4 seats. That said, if it all goes tits up and they no longer want to offer the suite option then they can still sell 4 separate seats without the need to renovate the cabin again.
Also, QR provide noise cancelling headphones in J class so any low level chatter shouldn't really be an issue.