User Interface is in the eyes of the beholder. Technical Specification is what it is made of. User Experience is in their mind.
How it looks is important, how it works is important as well, but both pale in comparison to the feeling a user gets on using it.
This is what most people miss out on. Architecture is the tech spec, UI is how it looks and UX is the feeling you get. Appiness, with its innovation and creative conceit, ensures that technically and visually, the project is perfect while providing a pleasurable user experience.
The trouble with so many of us is that we underestimate the power of simplicity.
We use human behavioural studies, psychology, and a variety of analytical tools to determine what users might like and then provide it to them. We realised a long time ago that in today's world, you cannot define user behaviour; instead, you must learn to decode their preferences and adapt yourself. we try to combine functionality with a pleasurable user experience and build marketing processes around it, rather than the other way around.
UI/UX design is not a new school of thought, it is the same human behavior which makes us prefer happier places over gloomy ones and pretty things over the ugly. It's a mix of eons of human behavioral pattern study following the best practices used in the past 30 years.