The point of Paladins is that they are lawful good knights, and thus would (or at least, should) follow a code of conduct dictating an honorable method of dealing with foes.
Yes, but the problem is that no one can really agree on what is or isn't out of bounds within the Paladin's Code. If you don't believe that, well, I can't point you to a couple hundred topics with a couple thousand posts apiece with people arguing back and forth about this or that point on the Paladin's Code. Yes, the rule against not using poison and not being allowed to ally with evil beings are fairly obvious, but that still leaves a LOT open to interpretation. For example, what constitutes Legitimate Authority? The PHB never says. And it was also the source of an argument between me and a DM, who said that even evil nations and tyrants constitute Legitimate Authority. Fortunately, the BoED says that even good countries don't constitute Legitimate Authority to turn a captive over to, if you know that they'll use evil actions against the prisoners (such as torture).
The Paladin does not echew these actions because they are inherantly evil, but because they are not lawful means of dealing with an adversary. You have to take both alignment modifiers.
And the arguments over the specifics of alignment are even more common then the arguments over what exactly the Paladin's Code covers. For example, you say a Paladin has to accept a surrender. Yet in the very description for Lawful Good, it says "Alhandra, a paladin who fights evil
without mercy...". Can you really not see how people can have disagreements over how to play a Paladin, the Code, alignment, and so on?
Just as a side note, a Paladin has to accept a surrender, but that doesn't mean they can't chain the villian seven ways to Sunday and haul them back to legitamite authorities (who probably aren't lawful good). Just because they're good doesn't mean they're stupid.
Agreed, though only because the BoED went at length about it. Prior to that, the only thing we had to go on was that bit from the PHB about Alhandra the Paladin showing no mercy. Though it's not as simple as you make it sound. Ok, so you're jumped by a robber in Waterdeep and before you can kill him, he surrenders. You can just trot him down to the nearest guardsmen a couple blocks away and turn him in. Easy enough, right?
What about the Paladin who's on an extended quest in the Underdark? Turning back isn't an option, and the PC's have to keep moving forward until the task is accomplished, before they can return to the surface. Ok, so a Drow from the band you fought surrendered and he's your prisoner, now. Ok, no problem. Hauling one prisoner around isn't so bad. Then you run into another group, and another Drow surrenders. Now you got two prisoners. Then you run into another group, and three more Drow surrender. Do you see the problem, now?
So you're on your extended quest into the Underdark, and you're now leading a chain gang of 7 captive Drow. On a mission which likely requires stealth, to boot. When I play a Paladin, I'll take captives if someone begs for mercy, now that the BoED has explicitly laid out that mercy MUST be given. But can you not see how that can be disruptive to a game? Either A) You have to go running back to the nearest good aligned civilized realm in order to turn in an evil-doer to the authorities every time you capture one, or B) You have to drag them along with you until you're done with what you're doing and can then return with them, the whole while risking having those prisoners give away your position, or escaping in the night and then overwhelming the party while they sleep, and so on.
Nevermind in a campaign setting like Ravenloft. The villains, in many cases, ARE the authorities. If you get attacked by Vlad Drakov's troops, and they surrender to you, who do you turn them over to? Though once again, I'm willing to swallow my disagreement with this bit, since I'm just glad to have an easy reference to look at for when it comes to the Paladin's Code. Not perfect, but it's MUCH better then the vague Code and sometimes contradictory alignment descriptors that we got in the PHB.