It's about the Tenth Amendment, Federalism, and States' Rights. When the Feds gain the power to enforce a right, they gain the power to violate it, which would result in the watered down protections we see for everyone with no alternative. As the article above said, after Kelo, many States instituted property rights protections against eminent domain superior to the Constitution, while others did not. Natural Law competition will show which is superior (and as you know, I side with protections for private property).
If you read the piece I linked (which I wrote), you'll see what I mean, especially as regards Federal enforcement of individual rights by "Selective Incorporation."
I’m not following your line of reasoning. Are you saying Kelo was decided correctly because it compelled States to pass laws on abuses of eminent domain?
What about the 5th Amendment? Was Kelo decided correctly with respect to the 5th Amendment?