Apparently Apple deliberately chose the 3.5 screen size in order to allow to allow single handed texting. In the diagram above shows the difference.
Another reason is battery life. Tim Cook says that the new OLED displays cause “design compromises”. One of these appears to be battery life.
This also explains why many Android phones are bigger. A bigger phone means a bigger battery.
According to a recent article the larger battery size doesn’t necessarily ensure more usage.
For example, the Galaxy Nexus (GSM, HSPA+ version, not LTE) comes with a 1,750 mAh battery to the iPhone 4S’s (again, GSM, HSPA+) 1432mAh battery. Despite the fact that the Galaxy Nexus’s battery is almost 20% larger than the iPhone 4S’s, battery test results show that overall, the iPhone 4S has better battery life:
• Talk Time: The Galaxy Nexus gets 8 hours and 23 minutes of 3G talk time to the iPhone 4S’s 7hours and 41 minutes. That’s roughly 8.5% more talk time for the Galaxy Nexus, for a 20% increase in battery size.
• Web Browsing: The Galaxy Nexus gets just 3 hours and 1 minute of web browsing over 3G, to the iPhone 4S’s 6 hours and 46 minutes. This is despite a larger battery.
• Video Playback: Again, the iPhone 4S is on top, managing 9 hours and 24 minutes of video playback to the Galaxy Nexus’s 6 hours and 32 minutes.
Those are terrible results, and keep in mind that right now, the Galaxy Nexus is being positioned as the best smartphone on the Android platform, the one all other Android phones should be measured up to. According to our calculations, though, if the Galaxy Nexus had a display the same size as an iPhone 4S’s, it would manage a mere 6.8 hours of of talk time, 2.5 hours of web browsing or 2.9 hours of video playback on a single charge. And keep in mind that this is just out-of-the-box: install any number of apps on your Android phone that suck down data in the background and these results would get even lower.
For enterprise users, a smartphone can deliver significant productivity benefits. A dead phone is just a brick. Consider this before investing in your next smartphone or tablet.