From my perspective, working on a desk or in a DAW is an additive experience that follows a top-to-bottom and left-to-right methodology. Most would agree that working in a downward fashion matches the same feeling as working from left to right. This is why tracks in SONAR (and every other DAW) are reflected like this when switching from the Track View to the Console View.
If you apply that logic to creating a new track with a track selected, inserting it underneath or to the right makes the most sense. This is also an additive experience. To invert that process feels like you're working backwards or in reverse.
Imagine typing a sentence and ".typed just you word the of left the to inserted was word every"
Doesn't make any sense now, does it?
What I'm trying to say is , I agree with your suggestion.
-DG