Absolutely ridiculous. Just ridiculous.
2, 3, and 4 (above) are not even exact duplicates. Not by a long shot. If your biggest fret is that Tidal Wave Bay is a copy, you need to take your complaint up with most every water park on earth that has a wave pool. It's honestly very, very absurd that you'd accuse Soak City at Kings Island of being a "copy" of Soak City at Cedar Point. It's not even worth arguing, though I know you'll attempt a snappy reply... Was the name "imported" from Sandusky? Yes. Every single other thing about the water park is exactly as it was when it was named Boomerang Bay save the action river and new wave pool.
As for WindSeeker, most anyone who's actually been on a handful of them will tell you that they give quite different experiences. WindSeeker, if it's easier to think about it this way, is an outdoor observation tower. Now, wouldn't an observation tower in Mason, Ohio provide a wholly different experience than an observation tower in Doswell, Virginia? Sandusky, Ohio? Buena Park, California?
But to argue that misses the point entirely, because the question is who cares? (EDIT: The answer to the question, by the way, is a vast, vast minority!)
Believe it or not, most of the folks who visit Kings Island will never, ever, ever (NOT ONCE) visit Carowinds. An overwhelming majority of Knott's Berry Farm visitors haven't the slightest idea that a park called Kings Dominion exists at all, much less do they know (or care?) that it has one ride in common. Period. If you traveled to Kansas City, Missouri and declared in your most accusatory voice, "You know, a park in Ohio also has Dinosaurs Alive!" guess how many people would give a rat's behind?
Something tells me that if Disney purchased Kings Island and decided to clone The Twilight Zone Tower of Terror (which exists in four places in the world), Star Tours: The Adventures Continue (which is cloned in 3 places), The Little Mermaid: Ariel's Undersea Adventure (which exists in two parks as identical clones), and Jungle Cruise (in five parks across the globe), you wouldn't mind at all. Am I right?