Most of these points already have been mentioned (e.g. ergonomics. My hands stopped hurting after switch to kinesis advantage. (but bevare of the so called “ergonomic” keyboards that actually are not)) There is anothe use case for fancy keyboards: a keyboard made for specific application. I you spend most of your work time in ProTools / Resolve / InDesign / expensive CAD, then an extended keyboard makes a lot of sense. A related example is the majority of cash registers: those apple/banana key grids? They are likely a programmable computer keyboard! Those are cheap and not “fancy”, though...