Thanee said:
I think my previous post made it fairly clear. The fighter loses attacks because he's forced to ready or delay to try and attack the archer. If he guesses what the archer's going to do correctly, they exchange an equal number of attacks. If the fighter guesses incorrectly, the archer winds up getting in more attacks.
Now if the Archer full attacked, he could full attack again and then disappear, but the Fighter can then also full attack (someone else

).
My scenario assumed two things. First, that the fighter and archer were facing off against each other. And second, that the fighter can't simply charge the archer's position. Perhaps there's a chasm there, or the archer's on a fortified wall. Or the archer has a fighter partymate with Hold The Line and a glaive.

The idea is that Shot On The Run allows the archer to make more attacks than the fighter.
And there are many other options for both, the Fighter could just run to the corner and deny the Archer his hiding place completely, the Archer then could try to find a new one. Basically both are occupied with each other, but the Fighter does not have to, the threat to be able to shoot the weak Archer alone is enough to limit the Archer's attacks, while the Fighter could unleash his full potential every round, by simply ignoring the Archer, whenever he does not present himself in full view (after a full attack).
Not quite. Again, my scenario was showing the usefulness of the feat, assuming that the archer has party support. Solo, I will agree that it's not so good, exactly for the reasons you mention. The fighter can charge the archer's position, etc. etc.
But as the archer in a party, it's very good. And no, the "threat to be able to shoot the weak Archer alone" isn't enough to limit the archer's attacks. It's exactly by mixing in full attacks that the archer gains the advantage. He can't be successfully predicted, so he forces the fighter to lose attacks.
Not, if he is doing "nothing" by himself in the meantime.
Whoever said anything about doing "nothing" by himself? The archer is attacking the fighter every round!
Yeah, in such a terrain, it's a moderately useful feat.
It ain't Power Attack with a greataxe, but so long as cover is available, it's a good feat. Thus far it's been my experience that such cover is usually available. YMMV.