I don't think it is at all. Good design is universal and sadly the marketplace has been duped into putting up with badly designed large phones (and their equally badly designed OSes) because Apple and every other company wants us as content consumption machines.

No thought ever went into the ergonomics of big phones and their OSes never adapted to fit. The reason Steve Jobs never made a phone bigger than the iPhone 5 was because he knew that 100% of a phone should be useable with one hand.