All of those "trivial changes" combine to give users the perception of completeness, cohesiveness and value.
When broken down into exacting detail, it's easy to dismiss them as imperceptible; by themselves, they mostly are. But the cumulative effect of these decisions leads to the perception of a better product.
Compare and contrast a MacBook Air with any one of the cheaper knock-offs. They may pretty much look the same, but the Apple product has an intangible sense of being worth more.
The same thing goes with cars—sure, they all have the same basic design, but put an Audi next to a Lada and you can immediately tell by looking at them which one's worth more.
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