> On a pocket calculator, you have one keyboard layout, and you simply ignore the keys you don't use. Has this ever been a problem?
Yes. There's a reason they sell basic stand-alone calculators, too, and it's not just price. There's a reason the ones for various tasks don't all look the same or have the same keys (a typical office desktop calculator is usually very basic, for instance). I'd bet money most calculators that exist are the fairly basic variety, not a fancy scientific calculator or whatever. Exclude the ones that were only ever used in school and never anywhere else and I bet it's an absolute landslide in favor of simple calculators. People are confused by the extra buttons, and don't want them.
[EDIT] Not to shit on this calculator, mind you, but this is another specialized one that won't be for everyone, not a universal solution.