Bruce,
I do the "OK" and the "ok" drives me up the wall.
I am late 40's.
But your daughter is right, anything in caps means "intense" as in angry or extremely excited. Just the only way they have to express emotion in this internet/text based world we live in.
'Cuz they have overused the exclamation point to the point that it now means nothing ...

And they know no other punctuation but exclamation points.