The DeDRM tools don’t work with lots of new books from Amazon. The days of easily stripped DRM on Amazon books seems to be coming to an end.

If you have an older Kindle, you can download the older format, I believe. I still have a Kindle DX for this.

True but it’s not ideal. You lose the typographic improvements that you get in the newer format. Still, it’s better than nothing and I’ve read that some people have purchased a used, older Kindle just to get access to the older file format.