I have seen a lot of mobile UIs in my time, but it is the worst. The interface fails to load half the time. The time that it does, it takes multiple taps to get it to do something. Multiselect is an exercise in futility, you'll get about 3 selected, then on the next select, it'll drop the previous ones, meaning you never select more than one reliably.
And they want to charge for it?
The ribbon really isn't the same thing as a flat look. The two are totally independent of one another. Take a look at this screenshot, for example: Windows 7 with visual styles turned off—no doubt familiar to anyone who's managed a recent Windows Server or used RDP. It's still full of the newfangled conveniences you loathe, despite being cast in traditional 90s bezels.
This is the point where the holier-than-thou crowd says you should know all the hotkey combinations for everything if you want to be efficient. Those never changed, creating a nightmare for anyone who wants to learn them in the post-ribbon Word.
Almost all of the biggest offenders were iOS apps, so if you never had an iPhone you were spared the vast majority of incidents where skeuomorphism caused problems. Ideally, you're right, skeuomorphism should be helpful, but many designers used it to create the illusion of quality by borrowing images and textures from physical objects that they perceived as being valuable. Here is a thorough breakdown of the nausea of the era.
It's a little sharper than that—the current generation of interface designs was a direct reaction to the previous decade's tradition of absurd skeuomorphism. The moment Steve Jobs died, Apple did an about-face and started following Microsoft's Win8/Modern/Metro UI lead. It may look like a step backward to those who from the Windows 2000 and Gnome 2 era, since there's a loss of visual cues, but the flatness of current interfaces is way better than what the classics became in the post-Windows XP era: bloated, overdesigned, pseudo-real-objects cluttered with mismatched shadows and conflicting perspective angles. You couldn't tell what was a button there, either! At least now there's a consistency and a return to the actual use of design guidelines.
That said, there are still a lot of cases where literacy in idioms dominates: for example, the largely inexplicable convention of swiping sideways on a list to reveal 'delete' or 'edit' buttons in mobile apps. That's probably where you and the UX designers run into the most difficulty. But two decades ago, every "how-to-use-a-computer" class targeted at seniors started with how to operate a mouse—so, as I think you've already recognized, it's important to try to take these things with a grain of salt, and recognize that no one is completely objective when it comes to understanding the culture of computer operation.
Slightly off-topic, but you have an interesting point. People need to stop getting so butt hurt if they don't have any direct reason to be. The ultra-sensitive person you are referring to used to be what was meant by "SJW." People overreacting to a perceived injustice where none existed. For instance my brother gets offended when people use the word "waitress." That's just stupid; nobody cares. (Of course, he could have been feigning offense just to elicit laughs... not sure.)
In fact, sometimes the overreaction is more offensive than the actual original event. For instance, when Trump used the perfectly acceptable phrase "blood coming out of her eyes" to mean "very angry and agressive" (which I think comes from horned toads), he became unsure of his usage and changed it to "wherever." It was pretty clear he was just not sure what the correct idiom was, and didn't want to sound stupid for getting it wrong. Unfortunately, SJW's assumed he was talking about menstruation. Nobody (at least not any guy) was thinking that, until the press started saying it. I'll bet Trump was just as surprised as anybody at the interpretation they put on his words. While Trump said some pretty horrible things over the course of the campaign, this was clearly an overblown response by people trying to make him look bad. (before you accuse me of any sort of ideology, please go through my post history)
The problem is that right-wing nut jobs like my buddy now use "SJW" to refer to anybody who disagrees with him on a social issue, or sometimes as a mythical straw man. That has made people like me become averse to the pejorative sense of the abbreviation. In fact, since it has taken on the broader meaning of "not an asshole," I gladly embrace the label. I've even posted on Slashdot that people should strive to become warriors for social justice. It's sort of like the opposite of what happened to the word "hacker." It used to have a good connotation, and now it has a bad one.
Now there is a caveat. It's something that caught me rather by surprised. Apparently there is a sizeable portion of the population who "just roll with it" even though they are deeply offended. I'm not sure what to do about that. I'm about to go way off the rails, so bear with me. I heard a story about a lady who did studies on people who cat call. One of the reasons they continue doing it is because nobody -- literally nobody -- has ever told them they were offended by it. He considered himself to be paying them a compliment. Whereas the women interviewed in the study were afraid to confront the people catcalling because the majority of them thought that would lead to physical or sexual assault. How fucked up is that. You have two people, both of them making terribly wrong assumptions about the state of mind of the other person. Honestly, I don't know which one I find more offensive: that guys think cat-calling is a legit compliment, or that a majority of women think random Joe-on-the-street wants to rape them. Like I said, I'm off the rails... sorry.
I guess the upshot is that maybe SJW's feel like they see an injustice somebody else is unwilling to talk about. Maybe the best answer is to have an open conversation with people that share different world views. See if your $MINORITY$ friend really has a problem with $PERCEIVED_INJUSTICE$, then act accordingly.
UNIX is hot. It's more than hot. It's steaming. It's quicksilver lightning with a laserbeam kicker. -- Michael Jay Tucker