I understand the OPs point on #1.
We had a 2E player who quit very early on in 3E because he had a real problem with an NPC with a longspear doing an AoO on an opponent who came up "behind him". And, the NPC with the longspear did not drop his guard to attack "behind" and himself provoke an AoO from the opponents "in front of him" (note: here, I am just using these phrases to indicate direction, and yes, I know there is no facing in 3E before someone has to state the obvious).
Gaming reality assumptions are very important for many players. Gravity. Direction. For example, the 3.5 rules do not allow an illusion to flank. But, the typical understanding of what flank is should allow for it (i.e. the target is having to devote attention to both flanking attackers). So basically, the illusion is worthless with respect to flank due to the flank game mechanic in this circumstance. On the other hand, an invisible character provides for a flank bonus to his ally, even if the target and/or the ally are unaware of him. Mystically, the target is suddenly easier to hit.
So yes, facing and other types of rules could result in fewer "plausibility" errors in the game mechanics for some players. Unfortunately, when that is done, more rules are added to the game and it becomes more complex instead of less.
I just hope that our group does not lose another gamer due to the bizzareness of 4E like what happened with 3E. Some people are quite set in their ways when it comes to gaming and gradual changes are sometimes better than drastic ones.