The term "competence" doesn't lend itself to easy definition-- even though everyone thinks they know what it means. And it means different things to different people. Isn't that interesting? It's certainly complicated.
So, I guess it makes sense that the rules of professional conduct which govern lawyers in the USA often vary in their definition of competence, from State to State. Why should something so foundational (for lawyers) be defined differently than what may be understood, or agreed to, by the rest of the population?
I speak, of course, with my tongue planted firmly in my cheek-- there are a lot of reasons for differing definitions or understandings, not the least of which is the distinction between personal conduct, and professional conduct. Social norms (which govern the former) are different than written rules (which govern the latter).
That said, the two do(or should) share at least one thing-- common sense. For instance, consider Supreme Court Justice Potter Stewart's famous statement (in drafting an opinion defining obscenity) that "I know it when I see it". Why not bring a bit of common sense to the definition of professional competence in the practice of law, so that it is understood to include one's state of wellbeing, contemporary with one's advice or representation?
Debate the manner in which wellbeing is to be defined, but at the very least, find a place for wellbeing in the debate. Argue about the degree to which wellbeing should be deemed outcome determinative, but for goodness' sake, allow room for the argument.
Competence is the sine qua non of what it means to be a lawyer, and our wellbeing is undoubtedly an important part of that. Let's allow a bit of common sense into our rulemaking process-- it'll no doubt be better for it!