Sure thing, Form should follow Function… but some designers haven’t heard of that. Like the Sony designers responsible for the two weird design choices below.
Round knobs are round because they need to be gripped and rotated… an optimal design for our opposable-thumb grip.
But the radio below has a round knob whose function is to slide right and left between two positions. There are wonderful switch designs for that, some going back to the Industrial Revolution… and their oblong form reflects the lateral movement. Not here, though…
And then there’s this little stereo system I use in my home office:
This has four shiny round knobs, of which one – at the right – actually rotates to control the sound volume. The other three are flush with the panel and are actually two-way momentary push-button switches – you push the top or bottom part of the control for a “click” that might advance the tuning or track up or down. The use of a round form here is an abomination, and each time I use them I go into a tiny cognitive dissonance. Fortunately, the sound quality is good enough to put me in a forgiving mood…