Restricting PvP to winged targets only would break the nation eco-system system yes, but IMO that system is already kinda broken anyway.
Also people deliberately stealing plants/crops someone else planted doesn't happen very often in my experience
This ascribes way more foresight and intelligence to Ankama's developers than I think is realistic lol.
And if Ankama's designers are such clairvoyant supergeniuses then why has the game been in a downward spiral for so long?
I'm sorry you wrote such a long post believing that anecdotal evidence was a hard counter to simple fact, but allow me to correct you. In Wakfu, PvP and the ecosystem are intrinsically connected. To change PvP necessitates changing the ecosystem feature as well. Neglecting to do so would leave the ecosystem feature broken.
When Wakfu was initially released, it was possible to battle other players anywhere and any time, with the notable exceptions of the tutorial areas: Incarnum and Astrub. There was protection against PvP for any character under lvl 13, but since those characters were free to wreak havoc on the ecosystem, the restriction was lifted and all characters regardless of level were on equal footing. At that time, it did not seem that players were especially surprised or upset when PK'd, because they understood that it was part and parcel to Wakfu's gameplay.
However, things became very confusing after the rules were changed to require the activation of PvP in a character's passport to make combat possible. Newer players were given the mistaken impression that PvP was in its own bubble separate from the main game, and by extension that it was a bug or oversight that permitted non-winged players to be attacked. In stark contrast to Wakfu at launch, where players who were PK'd understood that it was an instance of a human being wanting to experience an interaction with a fellow human being, today's players who get PK'd respond with a complete lack of comprehension, baffled at the seemingly inexplicable behavior of the other player. In their eyes, a player should only do anything when it tangibly benefits them in some way, and PKing unwinged characters has no such material reward.
How sad that the players of Wakfu see it as a grindfest and not a fun game that doesn't need be taken so seriously. The sandbox elements of Wakfu are one of the few key selling points it boasts over other MMOs, yet those features are being increasingly weakened over the years.