Elfs have "unthinkable" in hurting plants. They'll never accept anything made of wood. It is rather surprising they were willing to set tree cutting quotas above zero. It is hard to even think up anything outragous enough in our culture to compare it to trading wood to elfs.
"My God... What if the secret ingredient is people?"
"Nah, there's already a soda like that - Soylent Cola."
"Oh... How is it?"
"It varies from person to person."
*ahem* anyway...
Either you have Ethics or you don't. Now if there was a way to make your wood elf useable, perhaps through a ritual or something, I would support it because it ties into the fantasy environment.
While it is true that ethics only really matter if players don't just knock them over, there is something more that's at play...
Honestly, I'd be hugely excited if the game's civ/trade/diplomacy systems were eventually developed enough for there to be different "shades of gray" in societies - "True Elves" who stay true to their culture and principles (probably staying away from all other civs and refusing most trade), down the spectrum to "Multicultural Elves" from places or civilizations that are influenced enough by other cultures that they start adopting ethics of other cultures, and potentially even move towards cosmopolitan sites and civs, where no one set of ethics (or species) can truly dominate.
Right now, elven culture can only really mean "they have exotic animals" and "they hate it when you use wood", just as diplomacy really only comes down to "they're either at war with you, or not". The problem is that almost everything that makes them unique also makes players generally hate them to the point where killing elves is practically the biggest meme in the DF community (beating even "beards", and only really falling behind "magma"), and it doesn't really seem like that was Toady's intent.
In order to make "wood bins makes elves hate you" less of an annoying "gotcha", and more of a serious diplomatic niceity that has to be observed, you have to first make the entire act of diplomacy actually exist in a more nuanced form than "did you drown the last caravan in magma or not?"
For that to exist, you really have to start by making elves more useful alive and trading with you than it is funny to watch them die in magma. Maybe at some point where we have to trade for food or other types of goods, that will happen, or maybe at some point, elves will have some sort of plant goods with alchemical purposes worth trading for.
Likewise, it's harder to forget that you're going to accidentally offend an elven diplomat if you actually have to be involved in some sort of niceities before trade can start that involve reacting to the diplomats or traders in some way.
If we have a tavern and a system of letting traders come into our fort, and make themselves at home in our lodgings, and we have trades that take place without stopping everything and going into the menu, then maybe elves will only trade as long as the tavern/open area for traders to visit has non-wooden (or made-by-elves wooden) goods, and will be offended and stop visiting if there are wooden bar stools at the tavern. (Not that DF players need more reason to use stone for everything they can possibly get away with, of course...)