I'm not sure that always applies. I find myself much more productive on an RPN calculator, once I learned to use it, than on standard calculators, even though the learning curve was higher. I also find that with window managers, tiling WMs were harder to learn, but are a lot better now that I know how to use them.

I really like the calculator example. Imagine a buttonless calculator that just took dictation in plain english and gave the result for really complex equations.