What makes a good system?

When I was 15 years old, my dad bought me my first bicycle. It was brand new and I jumped on it and cycled round the house fast a few times before I crashed into my grandmother--even though it was brand new, the brakes didn't work properly. Luckily, she wasn't hurt. Then my dad came to me and said even if it was brand new, it hadn't been tuned yet. The same day, my dad took the bike to a shop. The mechanics in there removed the parts of the cycle one by one and then started to fit them in again after applying oil and grease. While they were doing this, they asked questions about what kind of seat I would like and whether I needed different lights, different pedals, and so on. Based on my answers, some parts were added and some parts were fine-tuned. In this way, from a brand-new bicycle, they made me a bicycle that was fit for my unique...