I think you might be misunderstanding. The 1 click ordering on Kindle books in not the same as the 1 click buying on the other part of the site. You don't need to activate 1 click to buy a Kindle book. It uses a different 1 click system. There's not been any changes to buying a Kindle book on the site that I've noticed and I bought a few just the other day.
I don't have 1 click activated either.