In my view, peak design is the "density" setting in Gmail where you could select between 3 degrees of density and wasted space in the UI.
Even though I like somewhat denser interfaces, I know that lots of whitespace is GREAT for new users. Just like I know everything needs to be in the UI (~80-90% of users click the undo button instead of typing Ctrl+Z in many apps). There has to be space for a learning curve for any interface.
The ability to make things denser is important, but high density is usually only relevant for power users. It should not be the benchmark by which a UI is judged.
EDIT: Actual ctrl+z statistic is inaccurate. Details included in a further comment.
> Button instead of Ctrl+Z
This is rather different, this is ignorance, so button alternatives are helpful for ignorant users (although one of the reasons for such widespread ignorance is precisely because there isn't really much of a learning curve since interfaces don't actually teach you much if at all)
But for a lot of whitespace instead of content, what exactly does it teach new users? Consider the toolbar example, how would showing a new user 3 buttons (left, right, section name) help instead of showing 3 buttons with section name and a 4th partial text button with section name?
Also, gmail density mostly affects vertical density, the number of horizontal tabs doesn't change, so the control density doesn't change as much except for the left list of categories (but only if it's a big list otherwise it would still fit in sparse UI ), making this mostly an aesthetic choice (unless you often need to see a lot of emails in a list)
Wow, I understand using the button on a phone app, because where would you even find the "Ctrl" button, but if it's true that even digital natives are still using the button instead of a keyboard shortcuts when sitting at a keyboard, that boggles my mind.
The statistic is actually wrong, I misremembered. It is from Tantacrul, a designer overseeing the current design of MuseScore and the redesign of Audacity. It's a finding he had while working at microsoft on a revamped version of MS Paint (the man has since moved to greener pastures).
The actual moment is a few minutes into the section about shortcuts (of a long video trashing a piece of discontinued music software). The actual bit was that undo/redo was the most clicked button in the MS Paint interface, and that people overwhelmingly prefer the button over the shortcut. No actual number is specified.
https://youtu.be/Yqaon6YHzaU?si=uDFFQgrbZuYFifhS&t=1580
The correct statistic (which I associated with the other example in my mind) was that only 17% of users use more than 20 shortcuts.