A point in usability in Unix™ vs Plan 9: I can never remember which program to use on BSD or Linux to take a screenshot. Grimshot? Maim? Import? What is all this nonsense.
When I want to do the same in Plan 9 it's just /dev/screen. I can get its size by reading it. I can save it to an image by reading it (it is an image). This goes with all the other things - they are files with the names one expects, instead of some weird-ass programs with strange names that may or may not work because of environment differences.