A good but puzzling question…
But I believe the rest of the industry sniggered at the iPod Touch when it came out, but when the popularity was established, they were too late to get into the market.
To think about it, the iPod Touch isn’t easy to mimic as consumers would not like to buy something equally expensive but with an inferior user experience. Not to mention, the large economies of scale that Apple enjoys is not easily replicable, especially with a tight flash-storage market.
iPads however, give competitors more leeway to try their hand at building something, with the perception of less difficulty.