Jef Raskin on “Modes, User-Preference Settings, and Temporary Modes”, in The Humane Interface:
Facilities for setting user preferences constitute an example of modes and are a major source of frustration. Ironically, these features are usually touted as a benefit. Present user interfaces are often so difficult to use that a user may feel an urge to rearrange them. Microsoft specifically recommends that such facilities be provided: “Users, because of their widely varying skills and preferences, must be able to personalize aspects of their interface … such as color, fonts, or other options.” [from Microsoft’s Windows Interface Guidelines, 1995]
… By providing preferences, we burden users with a task extraneous to their job function. … Time spent in learning and operating the personalization features is time mostly wasted from the task at hand.
… Customization sounds nice, democratic, open-ended, and full of freedom and joy for the user, but I am unaware of any studies that show that it increases productivity or improves objective measures of usability or learnability. Adding customization certainly makes a system more complex and more difficult to learn. I suspect that if you were to take a user survey, more people than not would be in favor of lots of personalizable features … [but as] has been observed in a number of experiments, an interface that optimizes productivity is not necessarily an interface that optimises subjective ratings.”
(I’m looking at you, Slack)