Good UI for tools, physical or digitial, should reduce the friction between picking it up and using it for something, that's the problem at the core of design. With the small caveat that sometimes technically good but perhaps unethical design solves stupid business problems well, like deliberately making chairs uncomfortable to keep traffic moving through a busy cafe, or making anti-homeless benches, design should not dissuade you from using something you purchased to solve other problems; it's unprincipled.