I totally see what you're saying, but I have fairly average sized hands and the regular size still seems just slightly too big to be considered small. I think this is because of the way I hold my phone, not hand size. I like to hold the phone from the bottom with my pinky supporting underneath. This makes it a bit of a struggle to even reach past the fourth row of icons above the dock for me.
My thinking is, if I'm going to struggle with one handed use with the small iPhone, I may as well struggle more or less the same but reap all the benefits of the larger device. Go big or go home in this situation for me

I am almost tempted to use a family member's old iPhone 5 for my daily device at times, I just love the beautiful design, the lack of slipperiness, and the slate black color. The compactness feels annoying but awesome at the same time, so quick and easy to use where my iPhone 6 gives more issues yet isn't even that much bigger.