Don't people complain that due to the actual size of the device, it's difficult to "shift" your hand to reach for the opposite corner of the screen? My understanding is that the physical size is a factor in the ability and/or inability to use a device one handed. People are always talking about "compromising grip" which increases risk of drops to reach across the screen.
That's what I often read about.
I also read that people actually do like a larger screen, but not necessarily a larger device, preferring edge to edge. If the Nexus 5 increases the screen from 4.7 to 5" but keeps or even goes smaller (FCC filing says the dimensions are smaller than the N4, no?) then I think people will be happier about that.
EDIT: Oh yeah, and let's not forget about the whole all those "it won't fit in my pocket" folks. Physical size would change that silly argument, too.
No?