If an artist passes away and their next closest kin is their daughter, don't you think that daughter should get the artwork?

Unless the artist specified something else in the will, yes.

Although ideally, if there is good will shared by all, the daughter might voluntarily give some of it to other family member.

Definitely

I would say, yes, then...
If it is the portrait of his brother for example, maybe his brother could claim it too for emotional purposes ..and make it somewhat more complicated..

If the artist still owns the artwork and not sold it, I think the art should go the the next of kin.

As long as there are no legal claims or specific designation in a will then yes.

Depends if there's a will

That would be the logical answer.

That would seem logical, unless the artist had specified otherwise; in a will, for example.

Shouldn’t even be a question

Yes, unless they put it in a will to someone else.