I don't carry my iPad around in my pocket. Unless you have an iPad belt holster, a bigger screen for the iPhone makes sense for people who are on the run, and don't have their iPads with them at all times.
It wouldn't be un-Apple like at all for Apple to increase the screen size. It'd only be un-Apple like for them to change the aspect ratio.
The majority of iPhone users would enjoy a larger screen; not the minority.
I wouldn't mind a slightly larger screen but I still would like to be able to use my phone with 1 hand. Anything larger than a 3.7" makes it difficult while still holding the phone firmly.