You're missing the point. Just because there's one problem with the iPhone, no matter how many people it affects, doesn't mean it's automatically a bad choice if every other feature is what you're looking for in a smartphone. If the antenna makes a phone 90/100 but every other phone is still at best 80/100, does switching platforms make sense? It's still a valid issue to complain about, but not enough to make the decision to abandon the platform for some people.
The point is, the iPhone is what these customers were looking for. They still like it enough to keep it, and they like it enough to complain when there are quality issues rather than switch.
I think you're missing my point. What do you want Apple to do about it? They gave everyone a free case with which it works fine. It wasn't a quality issue, it was a design issue. These are different things. No amount of QA will fix a design issue.
What possible other response from a customer service perspective could you want here?
The point is, the iPhone is what these customers were looking for. They still like it enough to keep it, and they like it enough to complain when there are quality issues rather than switch.