please give advice - hard reject, quality standards

I got a hard rejection (quality standards) my theme - Demo - with a comment:

“Unfortunately ‘WordPress’ has higher standards in terms of aesthetics. As higher quality items become available in the marketplace, approval requirements will increase to maintain appropriate marketplace quality.
While I’d be able to provide feedback as to how to get this approved, I can only do after it has crossed a certain threshold, quality wise. I’m sorry to say this isn’t there yet.”

Please, help me to understand, what needs to be changed?