Most people can tell you whether a product feels good or bad without being able to name why. There are two things going on at once, and they are easy to confuse. UI is the look: the color, the type, the layout, the motion. It is the visual feel of a product, the part you can screenshot. UX is the work underneath: the flow, the structure, how quickly a person goes from arriving to understanding, how the whole thing feels to actually use. UI is what it looks like. UX is whether it works, and whether using it feels good or feels like effort.
When the design gets in the way
Right now a lot of the web has the two backwards. There is an influx of heavy, cinematic sites. Full-screen animations. Scroll-driven everything. And increasingly, full 3D environments you have to fly through before you find out what the person or company actually does. I have landed on portfolios where I had to move a cursor through a rendered landscape, wait for assets to load, and hunt for the actual content as if it had been hidden on purpose.
That is the reverse of what should happen. The more work a site makes me do to reach the information, the worse the experience is, no matter how good it looks. I do not want to play 3D chess before I find out what you do. I came for the information, not the spectacle.
A nice design is ideal. Just do not let it take away from the experience.
Easy is not the same as good
The trap is that this stuff has never been easier to build, so more people build it. A 3D scene, a particle system, a custom cursor. All of it is genuinely impressive, and all of it is one tutorial away. But the fact that something is easy to do, and can be done, does not mean it should be done. Restraint is a design decision, not a gap in skill.
There is a reason google.com looks the way it does. It is not that Google cannot afford a fancier homepage. It is that the homepage has one job, and anything added to it would make that job slower. The most valuable thing a page can do is disappear and leave the person with what they came for.
None of this is an argument against visual design. Nobody wants a wall of unstyled text, and a product that looks careless reads as though the product is careless. But UI works when it serves the experience, and it fails when it competes with it. Decoration is what people scroll past to get to the answer. The answer is the product.