I think your opinion is a bit artificial. It seems there's a bandwagon of "chivalry was effectively absent, knights and nobles were rapist peasant haters" nowdays. It's most often the exceptions to the rule that go down in history.
Well, I don't know what history you have read, but I grew up believing in the tales of chivalry, damsels in distress, and king arthur and all that stuff. All of which, incidentally, was portrayed by hollywood in virtuall every single film I'd ever seen on the period, with the bad knights inevitably portrayed as exceptions to the rule.
When I got older and began to read first interpreted history, and then increasingly primary sources, I realised that that was a fantasy. The reality was viciousness, cruelty, the cynical use and abuse of naked force. Humanity can still be found in there, but nobility in the modern transmutation of the term (in the sense of being better behaved) seems very, very rare in any historical accounts I have read. Maybe you could point out some historical soruces (and I mean, history, not literature like the Chansons of Roland or propaganda like the King Arthur tales) which tell a different story.
Personally, while you might say people now days judge medieval knights by 21st century values, I think there is actually a disturbing trend among a lot of people who are into emulating historical combat of glorifying the people from those archaic times and white-washing their behavior. I recently read a discussion on a Roman history forum where some re-enactors said they wouldn't want to watch a realistic movie about the Roman because it would be "too negative". Negative or positive, history is history. Roman Legionaires, like Medieval knights, were tough, they were brave, but they weren't nice.
I'm sure most knights did't in practice go around saving widows and orphans, but most of them did display their chivalric virtues in prowess, loyalty, and largesse as their means allowed.
I'll grant you this, they obviously did have sometimes rather amazing prowess, and the one virtue you do see plenty of is a kind of extreme, sometimes quixotic fanatical bravery, which can be quite impressive, or ridiculous, depending on the circumstances. As for loyalty? Among knights and lords of the middle ages? Neither blood ties nor friendship seemed to matter much in the shifting political alliances of those times. Todays friends were sticking knifes in each others backs tomorrow...
Killing the heathen was a part of chivalry, as un-PC as it may be now.
Well this is a good example. Compare the "chivlary" of some of the Crusader knights to that of say, Saladin. Killing, raping, and torturing "heathen" women and children isn't exactly chivalric. Killing off half the population of Southern France, just because the Pope decides that they are suddenly "heathens", isn't chivalric. Wiping out a whole city of Albi because a small percentage of the population are suspected of being heretics isn't chivlaric. (this was where the cynical doctrine of "Kill them All, let God sort them out" was invented)
And neither is fleeing from battle the second the tide changes which knights were notorious for, and which is why they were increasingly made to fight on foot in some battles of the later middle ages (as at Crecy, Poitiers, and Agincourt) and how they ultimately evolved into an officer corps.
Naturally their courtesies were mainly applied to their peers, no one wants to extend the courtesies they follow to those not bound by them, particularly in combat.
Ironically, the peasants often did "extend the courtesy" of ransoming noble prisoners, because they could get money from them. This was one of many typical examples where the myth of chivalry (which was largely made up by itinerant minstrels, btw.) overlayed a reality based on money. Many Welch archers became rich by ransoming French Knights after Agincourt, for example.
(ask any infantryman if he likes being bound by the laws of war when fighting 3rd world terrorists)
Well, I was in an artillery unit myself, but I think most soliders with any concept of combat would prefer to fight in a front where the Geneva convention is being observed by both sides, rather than one where it isn't.
Against Germany in WW II, U.S. and English troops who were captured (and it can happen, no matter how brave or chivalric you are, you can be captured) had a chance of being decently treated. Russian Conscripts fighting in Chechnya, where both sides are "unrestricted by mamby pamby regulations!" and regularly commit atrocities, they can only expect to be killedm, and hope for a quick death if they are lucky .
They were only human, so the result must be somewhere in between.
The historical record, often in the direct voice of the participants in history, seems to indicate that times were pretty bleak. Of course humanity is varied, but knights were not paragons of mercy, justice, and kindness, any more than the church was in those days.
In general, it's one of the things I've always preferred about military history to more general approaches, because they miltitary accounts, being only interested in the details of the battles, are much less likely to whitewash the reality of what happened, good or bad, for ideological or sentimental reasons.
JR