I don't think calling something a ripoff is unfair. Yeah, they didn't invent those devices, but when they come out with their version of it which happens to be the first successful one. Then, after that device comes out every other company decides to be inspired by that it kind of is a ripoff. I'll admit that ripoff is perhaps a bit too strong of language but the sentiment is the same.
You can argue that eventually mp3 players would have succeeded, that smart phones would eventually all be flat touch screens, and that tablets would be cheap, not run a desktop os and successful. Truth is, we don't know because apple made those products a success first. To me actually making a product well, easy/fun/enjoyable to use is innovative. I really don't believe that we would see as many android tablets (well, tablets in general) if it were no for the ipad. I also still think the ipad is the best tablet because of the UI/apps and things mentioned in this article. The ipad also manages to be a pretty great price.