[PeterGriffin]

Your worries are completely unwarranted. Apple's direction for OSX is a trend setter. Due to sheer exposure, whatever Apple makes, becomes fashionable and most developers try to imitate it (usually that's good, sometimes it's bad). Case in point, while iOS 7 icons weren't something to call home about, many developers quickly redid their app icons as flat white shapes sitting on top of eye-gouging gradients.

[Yetanfou]

Uhhh... not to throw mud on your cake, but Apple has been following a trend with iOS for a while now and tend to merge more and more of it into OSX, hence these developments. When Apple was still lingering in a skeuomorphic pseudo-3D la-la-land, the world made a few turns and turned out to be flat after all. Whether it was Google following Microsoft or the other way around, both presented a 'fresh new look' which was mostly marked by flatness and abstraction. Apple followed suit in iOS7/8 and now in OSX 10.10.

[PeterGriffin]

Are you even replying to the right post?

I'm talking about the relationship between Apple and devs making apps for their platforms. Not about "who invented flat first" (answer: the 70s did, but that's another story).

Picking "who dun it first" arguments online is so old, dude. So old.

[Curmudgel]

Flat became popular in the '60s — the 1860s, that is, when Japanese art became available in Europe.

It became popular again in the twentieth century in the 1940s, but for somewhat different reasons.