OKCupid (OKC) realizes that it needs to evolve if it wants to stay relevant in the ever-changing online dating world. Specifically, it'll start retooling how messaging works very soon. Starting next week the only way you'll see messages from randoms is if you visit their profile page; the only messages that populate your inbox will be from people you've already liked or already responded to. Sure, there's the risk that you might not see a message from someone special, but if you've been proactive on the site that really shouldn't be an issue.
It's a little like how Bumble (seemingly the only dating service OKC parent Match Group doesn't own) handles messaging. To keep women's inboxes clear of unsolicited and lewd messages, the lady has 24 hours to make the first move before the match expires. This new feature from OKC should be a boon for anyone on the site, regardless of gender.