Single-origin coffee is defined by one thing: traceability. The beans come from a specific, documented place: a country, a region, a single farm, or even a single lot within that farm. Every cup can be traced back to a defined origin, often right down to the producer and harvest season.
Grind size can make or break a cup of coffee more than almost any other variable. Two identical bags, ground differently, will produce two different drinks.
Most people drink coffee by habit. They know what they like, they order it, they move on. Tasting coffee is something different. It is deliberate, and it changes what you notice in every cup from that point forward.