When the iPhone was unveiled, people were extremely skeptical regarding its lack of a keyboard. They feared that the usability of the device would take a huge hit and the device would fail. However the device succeeded hugely, with people noting that the lack of a keyboard was not that big of a turnoff. There were several reasons for this but most importantly it was due to the capacitive display that the iPhone had come out with.
Increase of responsiveness
Capacitive displays needed just a slight touch to register an action which was a huge departure from resistive displays, which needed a definite press in order to function. This made the usability quite a bit better and improved the usability quite a bit. An action always needed one touch instead of multiple presses, which was common in resistive touchscreens.
Along with that capacitive displays did not need to have an elastic top layer like resistive displays. Due to this, high quality glass finishes on displays became common which reduced the risk of internal screen layers being damaged. Also, the displays were quite smooth in their finish which ensured that the speed of touchscreen usage also improved by quite a bit.
Inclusion of Multi-touch
Another main feature of capacitive displays was its ability to detect multiple touches on the screen simultaneously. This helped in several applications as pictures could be zoomed in and out using pinch gestures which were a very convenient feature. It also helped in typing as multiple fingers could tap different keys at an instance and typing speeds improved considerably.
Multi-touch also helped in gaming and navigation software as we no longer needed to limit our on-screen interactions to single touches. Along with that the dependency on styluses also reduced heavily due to this characteristic as fingers became just as responsive as a stylus.