I've come to view my no-chopping policy as part of a larger campaign against "soft play." I would define soft play as any behavior that is intended to benefit another player or players at the table. Since this behavior is usually intended only to be nice, it can be awkward to protest it. However, when players are being selectively "nice" only to certain other players at the table, it becomes unfair. As a professional gambler who is wary of gambling in general, I am not comfortable when I'm in a game that I consider "unfair," even when it is relatively benign.
A few common examples of soft-play: two players may agree to always check on the river if it's heads-up, or they may agree to chop the pot in half, or a player may say "take two chips back" after raising. Sometimes, a player with just give $10 or $20 back to a losing player after the hand is finished. In my mind, the main problem with soft play is that it is akin to collusion and undermines the basic integrity of the game. In order to make good decisions in a poker game, I need to try to figure out my opponents' most likely actions, which depends upon having an understanding of their motivations.
In a poker game devoid of emotions and personal interactions, each player would be concerned only with maximizing his own EV, and the best players would simply be those who were best able to figure out how to accomplish that. In real life, of course, players have all sorts of motivating factors beyond. For example most players are at least a little concerned about their reputations as decent poker players, so they may be less likely to call with a long-shot draw (which other players will identify as a "lucky" play if the draw is hit) or might be inclined to show their hands at the end if they feel they made a great play. Or maybe two players don't like each other, so they try to give each other bad-beats. These and all sorts of other deviations from "pure" poker play are commonplace at poker tables, and, in fact, this is one of the reasons I can make money playing poker.
This is all fine and good. I'm not arguing that players cannot or should not consider factors beyond EV. (In fact, if they did that, over 90% of players would be correct not to show up at the casino at all!) In my mind, all motivating factors are fair game unless it can be construed as collusion.
I have more to say about this, but I feel I'm starting to ramble, so I'll leave it for a later time.
In addition to chopping, there are certain situations where "soft play" are so commonplace that I think people view me as cold-hearted. Here's an example that I felt a little bad about.
In a 20-40 limit holdem game, I had 44 in the big blind. Everyone folded to the button (a supposedly talented omaha hi-low player) raised. The small blind folded, and I re-raised. The button called. $6 is taken out for the house and the jackpot, so the pot was $124.
Flop($124) 998. I bet $20, button raised, I called.
Turn($204) 7. I checked. Button checked.
River($204) 8. Now I play the board. My hand was so weak that I decided to bluff. My opponent called the $40. I quickly turned over my 44. My opponent started to muck his hand, then stopped to think, and then turned his cards over (but he did not lay them on the table). I saw AK, which beat me. Then he mucked his cards. The surprised dealer pushed me the pot.
While I was stacking my chips, other players at the table pointed out my opponent's mistake. He took it pretty well, said something like "well, I'd better go home if I can't even read the board anymore," and left.