Pianists: "As a general rule, when trying to keep things easy we tend to think of F and C as being sharpened, and of B, E and A as being flattened."

All Music Software: "Fuck you, flats don't exist and all the black notes are sharps. Here are five sharps. Enjoy your sharps, nerd."

@miketorr most music software I've used you define an initial BPM, meter, and key for the project. Seems like software should use the key to decide whether to show sharps or flats.
@Thoracius That's interesting - I wasn't fully aware of the key signature being definable in software. It may well be, but it's never occurred to me to look for it or use it (unless I'm doing notation). Perhaps the best solution for piano rolls would be what you suggest - and maybe additionally allow people to reconfigure the note names to taste.