Made a nether portal pair where the destination coordinates match exactly (by a factor of 8). These portals have a "front" entrance, and are placed against a wall so their "back" is made of solid blocks.

Entering from the north side facing south on the nether portal, I arrive also facing south in the overworld. But entering from the south side facing north in the overworld, I arrive facing north in the Nether, ergo, face up against the wall! Why the useless 180 degrees orientation switch?

This occurs in lots of other portals as well.

Make it so the player's orientation NEVER changes.

Also, make it so that when a portal is automatically created, the new portal's orientation is the same as the other portal. Entering a portal to end up "facing" the side column looks even more stupider. Are those things really portals or are they some kind of carousels?

Portals should be: you walk in, then you walk out. End of story. They definitely should not be: you walk in, you rotate maybe 0, maybe 90 degrees, maybe 180 degrees, depending on which portal pair you used, and then you finally walk out.