Do you believe in good and evil? And that this dichotomy consists of more than just what's conducive to ridding oneself of dukkha, and in the end of much higher importance? That's the key. The Eightfold Path treats ethics like it's some kind of trifle--like it's a methodology, some "eight steps to success" program they're handing out to everyone at a business meeting. In the end I like to avoid wrongful action because it's wrongful.
Interesting debate.
I think you are mistaken in two respects. The first is in considering the Eightfold Path solely in terms of the individual. It certainly doesn't treat ethics like 'some kind of trifle' - you would need to provide rather more justification for that claim for me to take it seriously - but it
is a methodology, as you say, and the Buddha made that quite clear. It is though, not (just) a self-improvement programme for the individual but
the route to end suffering for all sentient beings. Something of such absolutely fundamental importance cannot seriously be compared to a better business program! Indeed, it's importance is infinitely more in my opinion than abstract notions and opinions as to what is good and what is evil, be they provided by gods, lawmakers, prophets or philosophers. We
know what is good and what is evil without having to read a book or have someone tell us. Can there be anything more important, accepting for the sake of argument that Buddhists have no Will of God or such to worry about? Can there be a better way of defining 'good' than "something that contributes to reducing suffering for one or more sentient beings" or 'evil' than "something that increases the suffering of one or more sentient beings"'? If there is, I've certainly never come across it - and it certainly isn't 'God says it is' or some variation on same.
In short, Buddhists "like to avoid wrongful action"
not as part of some self-improvement programme or spiritual quest, not because something is 'wrongful' as some sort of abstract moral principal, and not because somebody or something says it is, but because by (Buddhist) definition an action is wrongful if it increases the suffering of sentient beings.
The second point is that rather than defining Buddhist morality the Eightfold Path can be found within and intuited from what Buddhists call 'loving-kindness' (
metta). The Buddha himself put the cultivation and application of loving-kindness ahead of everything else as the first requirement of a 'Buddhist' life, not 'right this', 'right that', 'right, the other' or the combination of all eight. If Buddhist ethics have a centre loving-kindness is it... both the Eightfold Path and Buddhist ethics as a whole can be derived from there.