In Mac OS X, the red/yellow/green buttons in window title bars are much smaller and closely-spaced compared to other UI elements like toolbar buttons.
Making UI elements small makes them harder to click, especially at higher resolutions on smaller screens, when using non-mouse (trackpad) interfaces, or for elderly/young/disabled users.
But are there any benefits that might outweigh the obvious downsides? I'm mostly wondering if I'm overlooking something obvious here.
For comparison, here's pre-OS X Mac OS, where the button was square (larger!) and not close to anything else.
And also for comparison here's Windows 10, where the corresponding buttons take up the full height of the title bar, are about as tall as toolbar buttons, and are much wider than they are tall. Although I like many things about OS X, I personally find this part of Windows much more usable.