I don't understand the need for a large phone. If I need a large screen, I just use my laptop or desktop. Moreover, without a proper keyboard I mostly just read a tad bit of text. You don't need a massive screen for that.
Photos look better on a larger screen. Especially when you want to show them to other people. Say, you meet some friends in a café, and want to show them your vacation photos.
You can fit more text on a larger screen, which makes it better for reading. You can fit more icons, widgets, etc. It's easier to do precise taps.
Basically, I want a phone as large as it's possible without losing ability to operate it with one hand (that's when you get a tablet).
