[adambware]

They've added padding to the design nearly everywhere - "menu bar is now taller", "Dock is lifted from the bottom", and the extra padding on the Sidebars is obvious.

As a power user of a Macbook Pro, this is cutting into my screen real estate and not very appealing to me.

[haroldp]

But think of all the space saved by turning every web browser's title bar into tabs or location bars. So what if you're left with 8 pixels to grab a window with your mouse and move it!

[chadlavi]

If you're a power user, you probably know that you can hide the dock and the menubar

[adambware]

My dock is tiny and pinned to the right so I can use as much vertical space as possible. This might push me to adopt hiding the menubar.

It's more about the compounding effect when other apps adopt this more spacious UI pattern for their title bar, sidebar, etc.