Thanks Christina. I did not mean to 'justify' emotion. However, I do not think that emotion and regulation should be contrasted as much as they are, when many people discuss these terms. And I do mean scientists as well as non‐scientists!
I believe that we call emotions is an integral part of a regulation system - or integral parts, plural, because I believe we subsume several functionally related processes under the heading emotion, even if they differ with regard to when and where they happen.
When you say that emotion is an expression, I do not ask "expression of what?" but "why is it expressed?" - and here I am not talking about each individual case but generally. The question, for me at least, is not why person x showed emotion Y in the situation Z, but rather why tend people to show Y in situations of type Z. So the thought here would be that something is expressed to achieve something - either in or for the expressor directly, or for others, which probably means for both. I believe that if there is a systematic pattern of Y to be shown in situations Z then it is a mix of biology and cultural constraints that shaped that pattern because it serves a particular function. The function is what would cause that link to become stable over time.
The function could be to get attention, to appease, to threaten, etc etc. This is what I mean with regulation in the sense that relationships with others are structured via what we call emotions.
What do you mean with "concern" in this context? Whether the situation that is associated with the expression is of personal concern to the person who is in the emotional state?