I find your point about the onyx core drop rates in wilderness events quite intriguing. Like you, I've been eagerly anticipating this drop but have yet to acquire it, despite its 1/400 drop rate. Your experience of participating in 700 events without success definitely highlights the rarity and challenge in obtaining this item.
From a different perspective, I do see the allure of finally getting the onyx core as a drop. The prospect of selling it for a substantial amount of GP is undeniably tempting. It represents not just an achievement but also a significant financial reward within the game.
Regarding the suggestion of a bad luck mitigation or a drop rate enhancer, I'm somewhat torn. On one hand, a slight adjustment to improve the odds could indeed benefit those who've been grinding tirelessly. It could make the process feel more rewarding and less frustrating.
However, on the other hand, there's a delicate balance to maintain so as not to overly inflate the supply and consequently tank the market value of the onyx core. The rarity of the item is partly what makes it so valuable, both in terms of GP and the sense of accomplishment in obtaining it.
Perhaps a middle ground could be found. A modest increase in drop rate or a system that slightly improves odds for players who've participated in a high number of events without success might work. This adjustment could acknowledge the efforts of dedicated players while still preserving the item's rarity and market value.
Finding the right balance between rewarding player effort and maintaining a healthy game economy is crucial.