The iPad is the pinnacle of the marketing job of making people forget everything that came before :)

But, seriously, Haskell, for example, is quite practical (better than the imperative languages) for a big set of applications. One problem is that people want a language to rule them all - and that language can only be imperative; the other problem is that people don't want to learn different things, and a new paradigm is as different as you can get in programming. That makes everything else unpopular.