So, for example:
So, assuming backpedaling/pursuit over at the same time: My lightly armored ranger wants to lure a heavily armored fighter in a trap where the party’s thief lies on wait to strike. My character elects to use his full move and simply defend. He backpedals 20 feet. The fighter pursues until 20 feet, his full movement. My character continues to backpedal, and the fighter gets an attack.
Assuming that the movement is separate: same scenario, but the fighter gets an attack because he moves second.
Assuming the fighter isn’t lured into the ruse: My character backpedals, the fighter elects not to pursue. He gets a free attack.
Other various scenarios: the fighter can follow the whole way, this altering his movement ability. The fighter /must/ follow, which means that my character must do the same thing without my consent to do so.
All in all, it does make sense since there seems to be a difference between backpedaling and actually fleeing. Fleeing from combat and incurring a -2 to AC and free attacks make sense—you’re turning your back, lowering your defenses leaving. But it explicitly says that when you backpedal, you’re still defending.
I understand that there advanced combat maneuvers (dodge, parry and block) that can be done with backpedaling, so maybe you’re right, but it seems weird to define two things of they are, in effect, the same thing.