What I expected:
I expected the Wither I just created to face in my cardinal direction, or at the very least, for the Wither's orientation to correspond to its totem's orientation.

What actually happened:
Withers always spawn facing South.

How to reproduce:
Create Withers, and watch which direction they face initially.

It is really more an aesthetic thing than anything, I'm sure. Especially for totems where the arms point North-South, where you see the Whither emerge 'sideways'. It seems to detract from the idea that they emerged 'from' that Soul Sand structure.