Me too, one of the biggest reasons I jumped from Android to iOS 18 months ago, I didn't like where the size was heading in the higher end Samsung, etc phones..
Android is not power-efficient, and Android apps you get can devastate battery life in ways that can't happen on iOS.
Solution: bigger battery!
But where to put it?
Solution: bigger screen
That said, a bigger screen is also better in its own right.
And also worse: small is nice in other ways. A personal call to make.
I like the current iPhone size, but if I have a second choice of size I won't complain at all! I'll hold both in my hand and decide. I certainly don't object to the benefits of the current 4" screen--and I do object to the many problems of Android (lack of updates over time, lack of security).
(And a big screen certainly makes good "impulse marketing" at first glance: like setting a TV's color overly garish in a showroom: looks goof on the shelf! And for spec-number fans its a plus even if they may also find it bulky to deal with. So, some segment of people WANT bigger screens. I have no doubt Apple will give it to them.)
Think how the PowerBook, iMac, MacBook Air, iPod and iPad diversified as their sales reached higher volumes: products naturally split into more options over time. I'm sure the iPhone will see the same thing happen.