Screen size is the larger issue. Operating an iPhone vertically isn't onerous. Significant wrist fatigue on a large screen occurs regardless of tilt. "Touch su

Screen size is the larger issue. Operating an iPhone vertically isn't onerous. Significant wrist fatigue on a large screen occurs regardless of tilt. "Touch surfaces don't want to be vertical" is most likely SJ bending the truth a little. What Apple's user testing certainly showed them as the 'high order bit' was "Touch surfaces don't want to be big." SJ wouldn't be eager to mention size because critics and reviewers could have quoted him when discussing iPad.