Are we trying to get people to READ? Or are we trying to get people to ACT?
You guessed right: ACTION is our real goal.
It doesn't have to be immediate action, by the way.
Great thanks and good newsletters foster warmth and can instill amongst your supporters a sense of accomplishment. Great thanks and good newsletters mostly do NOT ask for any immediate action (although offers and "soft asks" in newsletters are fine).
What are your thanks and newsletters supposed to be doing?
They're fostering retention (also known as "donor lifetime value"). And better retention simply means that your readers will ACT again.