[notalaser]

(Actual) HCI experts didn't join the computer industry when smartphones popped up. They did when GUIs became a serious research subject for the industry, back in the 1980s, and a lot of their expertise and effort went into computer interaction throughout the 1990s and 2000s.

Frankly, I cynically suspect that the flat, semi-functional design became widespread when the revenue model of many computer and phone vendors started overwhelmingly relying on super-revolutionary "apps" being churned out on minimal budgets.

Today, you can get a complete design for the kind of money (and time) that got you a really good icon for an OS X application back in 2005. It's a major step back in terms of interaction model, not only looks, but the consumer industry runs on money, not quality.

[Grangar]

The problem is that UX became a buzzword, and now unqualified graphics designers are 'practising' it. It's hard to find an actual UX designer, and as a UX designer it's hard to find an actual UX job (as opposed to a job that labels itself as UX but is just graphic design)...

[notalaser]

Indeed. That's why I said it's a step back in terms of interaction model, too, not just graphic design. The applications sure look awful, but the interaction is increasingly bad, too (just look at the hordes of UX "experts" who religiously follow the Cult of the Hamburger Menu).