Yeah yeah YEAH!
(I agree with you a lot here)
Side fluff can be super important.
Having players engage consistently with one element/activity is fine. The more that one thing dominates the games design... well that
can lead to problems.
Some games are 80% one activity with some peripheral things for the player to do (like many racing games).
And that's not inherently bad.
Some games are 100% their core activity... like Tetris.
And Tetris rocks!
But raiding? Is that a strong enough core to build a large percentage of your game around?
As fun as it is, I personally don't think so.