There's plenty of middle ground between the current extreme flatness and, say, MacOS X Tiger. An interface with a simple 3D bevel look (such as in Motif or the toolkit in NeXTStep) is no more skeuomorphic than than a flat interface, especially not considering how prevalent touchscreen controls are today.

Flatness to the current point of minimalism is, to me, very taxing and complex. Things blend together so much it's hard to tell where one UI element begins and another one ends. I frequently misclick in Windows 10/Office 365 even though I've used it for years now, simply because the flatness makes me misinterpret the layout and function of the UI.

I miss the look of MacOS X Tiger so much. It was a thing of beauty.

Complexity is good if it allows you to see affordances more easily.

Maybe buttons should look different from non-clickable icons. That requires some complexity.

I don't disagree that complexity can be good! I was just correcting the "longing for that simplicity" statement, which was incorrect.

Flat design is way too simple.

I liked the 3Dness of the buttons in Windows 95-98.

You knew if something was clickable right away.

Easy isn’t always so simple.

Correct, but flat design is objectively simpler than skeuomorphism.

I don't even mind skeuomorphism, I quite like it, but it's just bullheaded-error that has people claiming that it's simpler than flat design.

Complexity isn't a sin or something.