You have earned my respect because almost nobody seems to get that one. I've whined about it for several years and most comments sum up to "who cares?". It's little things like that which streamline the user's experience.
To sum it up for those who haven't heard my rant yet: If the headphone jack is on the same side of the phone as the volume buttons, then when put into a belt pouch, you can change the volume without removing the phone. The side of the phone which has the headphone jack is always on top of a pouch by necessity. Just think about it for a second.
I totally agree with power buttons on the side too. Even without a pouch, it's so much easier to turn a large screen on and off if the button is on the side. It's just a flex of the thumb or finger.
Ergonomics!!