Users' expectation changes. You ask someone who grew up with Windows 98 and they will tell you that d'oh of course onscreen buttons should have a depressed state to indicate they are pressed. You ask someone who grew up with Snapchat and the entire idea of having buttons is optional: tap on this area of the screen for this functionality, tap on that area for a different functionality, and swipe left for this swipe right for that with no indication that the UI is even swipeable.

It is perhaps a problem that there are a lot of visual designers around, because that is something for which a classical education exists and which has a certain prestige, and very few UX designers, for which no classical education exists and which seems to have little prestige. Good UX design is usually not fancy, form follows functions isn't flashy, and the whole thing seems kinda nerdy (not cool).

About the return of skeuomorphism, I do believe it's happening because people are fed up with flat everything in two colors, but I wish there was less oscillation around the center. As many have mentioned, Win2k was very good, and it was a middle ground between the extremes we're seeing today. Actually, it was extreme in one way: you could tell what a UI element was going to do without trying to click every pixel and seeing what happens.