It's just less simpler than the home screen with a nice background, however, there is no reason why anyone would open the dialpad to carry this experiment.

All one would ordinarily do to check call strength is look at the home screen. For me the dialpad is a very infrequently used app, and I rarely use it to make calls.

In any case, why are you so hostile to the idea that Apple was being intentionally malicious? If I were trying to discredit a competitor's product, I too would choose the most unattractive space I could to highlight it. Given that the signal strength is shown in most apps, you certainly have a wide choice.