It would be great if we could have open ebook reader software that could display these books.
I agree, but it also would be great if DRM wouldn't be use to restrict your device choice. The only reason Kindle DRM "works well" is because Amazon is basically the biggest eBook store in the world and Kindle are the most popular brand. But you can't buy a book in Kindle and use it in a Kobo device, for example.
DRM would be slightly more acceptable if the companies themselves didn't use it to also enforce their device lock-in (e.g., license their DRM to other companies), and so we are in the current situation where there is device lock-in and you are required to buy a eReader from Amazon if you want to read Kindle books, or at minimum buy one of those Android eReader devices since you can install Kindle app on it (but in this case you have all the other issues that you get by running Android in a eReader).