I have been thinking more about the renewed earth. I think it relates to the renewed physical realm. Here's a quote from the message I mentioned a few days back about the New Heavens and the New Earth.
“And the ultimate reason there is a new heavens and a new earth is because the risen Christ will never lay down his human body but keep it as an everlasting emblem of Calvary where the glory of God’s grace was most fully displayed. The whole material universe was created in the first place, and then given its new form, so that the Son of God could be incarnate as a man, suffer in the flesh, be crucified, rise from the dead, and reign as the God-man and be surrounded by a countless host of redeemed people who in our spiritual bodies sing and speak and work and play and love in ways that visibly reflect his glory most fully precisely because we have bodies in a world spiritually and physically radiant with the glory of God.”
It's mostly about our bodies. I think some of what Piper is talking about applies to all of creation too.
Bottom line: It's for his glory!