Design screws up functionality

Last weekend I staid in a nice hotel in Reims, and I was again frustrated by the shower. It's not the first time that I see a shower with knobs that are almost circular, with just a little bulge. Didn't the designers realise that this is hard to turn, especially if your hands are covered with soap? At home I've got these old-fashioned knobs that are somewhat triangular, that you can easily turn if you're all soaped up, even if it's with your feet.