> So why does everything look the same (even to the same colours, locations (responsive & fixed) and sizes) after spending all that money and effort? And when something looks/behaves different, 'normal' (not in IT) people find it annoying to use?
Really though? Does your web browser interface look the same as your sms/messaging interface, look the same as your car's annoying infotainment interface, look the same as your mail client, look the same as this website, look the same as your search engine? Do all of those things really look the same as they did 10 years ago? We use so many interfaces that are subtly shifting and being improved that the ones that work well for right now don't even stick out to us, and that's part of the problem. If you don't really notice that you're using an interface and are entirely focused on solving the problem you need to solve with that tool, then that's probably a really well designed interface. It's probably so smooth and intuitive that it seems like designing it that way would be obvious, but it's really, really not.
> If I have to work with something often (all day let's say), I want UX and I couldn't give a shite about UI; I want things easy to find, fast (not latency) etc. Combined would be great, but tell me what has that, because I always see one, never both done to perfection. If there is a 50/50 mix, it's usually annoying as hell on both sides.
You don't have an particularly accurate understanding of these roles. If a UI doesn't let advanced users solve their problems efficiently, then it's a shitty UI. "Pretty Pictures" where not appropriate is bad UI design no matter how pretty it is and people who don't think so are visual designers (at best) trying (and failing) to be UI designers. A well designed UI is an effective UI. All of those pretty UI mockups you see on sites like Dirbbbbbbble and behance are nothing more than aesthetic explorations. There's no way you could even know if they were good or bad UIs because you don't know exactly what problems they were trying to solve, for whom, and in what context.
UX encompasses the entire experience. If you have a great UI but the world's shittiest email confirmation workflow, then you have a UX problem with a great UI. This misconception is why developers think adding the ability to select color themes in their application with a horrible UI will address UX problems-- which to any actual software designer is complete nonsense.
> My most productive interfaces are ugly as hell[...]
A couple I'm friends with had a broken kitchen faucet handle for ages-- it would just fall off unless you held it on while operating the faucet. Unfortunately, one of the necessary connector pieces was no longer available, so it wasn't a trivial fix. Once, when I was pet sitting their rabbits, I got so annoyed by the thing that I went home and made a wooden piece to fit in where the missing part went, and fixed it while they were still on vacation. It was supposed to be a surprise but I totally forgot about it, and a few months later my wife said to them "hey do you like having your kitchen faucet fixed?" They looked at her, perplexed, walked over to the kitchen faucet, tried to pull it off, and it obviously didn't come off. They were shocked! Why? Because they were so used to holding that damned handle on the faucet that it just became an part of their using that faucet.
So not to be flip, but, the sky is blue, water is wet, and technical people are tolerant of and used to using shitty interfaces. Open source user interfaces are almost exclusively used by technical people; there are a few exceptions like Firefox, but Firefox's interface is managed by a team of foundation-funded full-time professional designers, (actually they do a lot of really great open usability work.) One exception I can think of is Inkscape. Most open source interfaces are absolutely awful. Why were they designed that way? They weren't. In fact, they weren't designed at all. They were assembled, ad hoc, to expose functionality in a way that made sense to whoever was creating the functionality. Those interfaces, more often than not, are more representative of their implementation than the problem they're solving, and unless you have a working mental model of how software works, and often specifically how that exact process works, the interfaces are practically useless.
There's a big difference between harder-to-learn-but-amazing interfaces-- vim, emacs, oboe, airbrush, airplane, etc. -- and interfaces that are entirely unedited. People are always going to be most productive using interfaces that they're used to, and that often mistakenly leads them to believe that what they're used to is objectively good. If you ask nearly any group of professional photographers how many hate Adobe, most will raise their hands. Ask them how many have used Gimp, they'll almost all raise their hand. If you ask them how many used Gimp more than once, they'll almost all lower them. Ask them why, and they will almost guaranteed cite the poor interface. While many dedicated and experienced FOSS developers (which I am) will cite Adobe's marketing practices as the reason people use Photoshop instead of Gimp, I call bullshit. You'll find many more photographers using Affinity Photo than Gimp, and considering Gimp is free, that says a lot. Who will you find using Gimp? Developers that need a photo editor. Why? They're so used to holding on the faucet that they don't even recognize when they see a properly working one. (And they'll often get really mad for even implying it needs to be fixed.) You also don't see that split with Inkscape. Most people who professionally work with vector art choose Illustrator as their primary tool, but most of them cite exactly the reasons developers assume people continue to use photoshop: overall smoothness, ecosystem integration, file type compatibility, etc. There are some legitimate shortcomings in Inkscape-- the type tools are just not as good which matters for graphic designers, for example. But lots of people who do vector art professionally do use inkscape.
Regarding Instagram et al, before you question whether or not the interface designer did a good job communicating, you need to know what they were supposed to be communicating. I'll bet they did a fantastic job at surfacing what what marketing people thought was useful for marketing, sucking in people's attention, and funneling them into profitable paths. The problem isn't that they're bad at it— the problem is that they're good at it while working for an organization that has shit motives. Similarly, the developers that make Instagram are still very very good developers even if a lot of their energies go into making super shady privacy-smashing telemetry. The problem isn't developers or software development, it's the goals handed to those developers.