I was recently in an elevator and someone ran in looking like they were in quite a hurry and started jamming at the button to take them to their floor. The button had lit up in bright red right after they had pressed it the first time, indicating that their input had been registered. Nonetheless, the person continued to press the button a few more times.

Right above the switch board with all the buttons was a plaque with text in small print that read something to the tune of "There is no need to press the button repeatedly. If you press it once, it will light up to let you know that the input is registered."

I often see products designed in this fashion. 

Putting up such text is a cop out as opposed to good design.

Someone who is frustrated enough to press a button repeatedly is certainly not in a frame of mind to read small text that explains to them that they don't need to do so. If anything, it only infuriates them more if they happen to read it later. 

Instead, good design tries to reduce the frustration. Perhaps by telling the user the estimated time it takes to get to their desired floor. It's far more reassuring to see '30 seconds to your destination' pop up instead of the text on the plaque.

When talking about recipes, it is almost cringe-worthy nowadays to hear that the secret ingredient that makes the dish so much better is "love".

But, it is quite apt with product design. When the designer goes about their job with care and love for the user, they design much better experiences.