Salute Gents,
Chute shooting is a controversial subject, no doubt. My personal feeling is that someone that shoots chutes is, A. Trying to rub it in, or trolling. B. Trying to pork your score by messing with your kill/death ratio. Or C. Trying to remove a possible source of information to the enemy. I only consider the third motivation to be acceptable, myself. People are wasting ammo when they shoot chutes, thus limiting their own ability to defend themselves when attacked, and their ability to do meaningful damage to the enemy. Thus they are acting in a way inconsistent with teamwork. (we never see anything inconsistent with teamwork in AH do we?)
I fly in such a manner as to always be an asset to my team. I look at the map and see where I can do the most good for Knights. That might be doing something I don't particularly enjoy, or am not particularly good at. The team comes first though. Not everyone plays this way. Make no mistake, I don't expect everyone to but it WOULD be nice.
I have been known to take up a zeke at an airfield under attack by 10+ cons. This is heck on your kill/death ratio. However, if I can fly little patterns over the field and frustrate those 10+ cons long enough for the ack to return and hangars to come back up or pilots to get off the airfield without being vulched, the enemy won't get that field. Furthermore, they will be essentially wasting the resources sent to take that base (the 10+ pilots trying to shoot me down, rather than taking the base). In this manner I have done the most good with the least resources (one pilot and a zeke).
Back to the subject of chute shooting, I will use an old t-shirt slogan to describe my feelings on that... "Mean people suck".

People are going to do whatever they wish, nothing to be done about it, I think it is poor sportsmanship and definitely a sign of a character flaw to do it for any other reason than to prevent chute spying. I disagree with some others that it is acceptable since it is not real life.
I do not alter my behavior simply because I am in a game, I do what I should do, or what I feel is right ALL the time, period. I have stayed in a fight with no ammo because my wingie was outnumbered and the enemy avoiding me getting on their six (they don't know I am winchester) may improve his chances for survival. Yeah, it's just a game, but you are either honorable or you ain't. Saying it's just a game doesn't cut it IMHO. It is an excuse for your behavior, and why excuse it if it is something you are proud of?
GIJeff