Truth be told, I'm now hooked on OneNote. I have ample free storage without bandwidth limits, and the client apps are really nice.
I've become a daily user of OneNote over the last 12 months or so but didn't know there was an active eco-system to add-on.
But then again I doubt google wants to throw so many users at a product that's not ready for prime-time yet. You don't want to throw a large crowd of late adopters at an early stage product.