Being as I was away from the game for about 2 years and just came back about a month ago, I would have to agree with your assessment. The LW arenas have much more of the first person shooter mentality than they used too. For the most part though I have tried to remain faithful to the style of play that I believe in. I will not steal a kill, I don't jump into a 1v1 unless I know my teammate is in trouble etc... the one exception to this is HOing. I find that each time I try to refrain from it in the LW arena I just get shot in the face. So I have given up my grasp on that level of chivalry in the LW.
I do find that in the MW and EW it seems to be less prominent. In these arenas I will only use a HO as a last ditch, have to save my bacon, effort. I actually had one of those moments the other night fighting RVFlyer in the MW. I was in a D11 against his Spit and it was the only option left after he pulled some great evades getting me lower and slower each pass. If I remember right the fight turned into a draw as I had to extend out and couldn't get the kill. It was one of those fights that keep you paying the 15 frog pelts a month to play.
I will add that it is not always the case in the EW/MW arenas. I was in the EW the next night and was in a 3v1 fight, me being the 1, and I was getting ho'ed by all 3. A bit sad but all part of the game.
Lastly I say fly the way you feel like flying. If your ethics say "don't ho" then don't do it. But certainly don't expect that any other player in the arena will follow your beliefs. Your chivalry may get you killed more often and it may effect your score, but you at least can know that your doing your part to keep the game from turning into Doom with wings.
Big Mickey