Well, I think that is not a self-evident bad thing. As a result of Android and Windows Phone design guidelines, by far the most interactions happen on the bottom half of the screen. I think that as long as you can reach the notification bar, there's a pretty good argument to be made that the additional screen estate is more beneficial.
Furthermore, just because you're used to it on your current phone should not necessarily imply that you need it on your next. That is a line of reasoning I'm also seeing a lot, but that just sounds like people being conservative to me. It's a fine preference to have, but such a slightly different way of using a new phone may not always be a bad thing either.
I'm not arguing that bigger screens are better, but I don't think that there are clear objective constraints to screen size. You could even wonder why people think one-handed usability is important at all.