Camera Tracker in my experience is a very capable, powerful piece of software. Dont be distracted by things you learned many years ago. I works great and creates amazing camera tracking data in most cases.
I agree with both of you. Do not be distracted by things you've learned a lot time ago, since technology is constantly changing and we need to change with it. However, the rule to animate the rotation, and only set the orientation once is a good one for many reasons. I too would love to have an option in AE to either convert Orientation keyframes to Rotation keyframes, or simply be able to pick wich one I'd like to have animated after the track.
If you are talking about animating layers instead of cameras then it's usually easier and more efficient to orient rotation. What you learned is valid.
AE's camera tracker uses a single node camera and calculates camera orientation to try and match the movement of the original camera. Some shots, like a 760º pan are impossible for the AE camera tracker to calculate so other techniques must be used. Just because the 3D camera tracker animates orientation this does not suggest that the technique is best for all 3D layers.
BTW, converting orientation to rotation and having the behavior remain the same involves much more than simply copying values. Orientation and rotation are indeed two different properties and you cannot do things like pan a camera around 2 times easily using just orientation. You quickly run into things like gimbal lock using orientation. Think of orientation properties like a pan head on a tripod. Rotation has no limits.