Disposable addresses are a core part of the product, so it can't be disabled. However, disposable addresses have many uses. I use them for things like signing up for trials of software and services, for downloading eBooks on coding and marketing, downloading industry white papers, etc. I use it at least a couple of times a month, and sometimes more. I find it easier than creating a content filter or using a plus address as a) it's quicker, and b) it has a strict time limit so I don't need to worry about going in and disabling it/deleting it/managing folders. That said, some will use them for other reasons and some won't use them at all. SmarterMail is a product with a set of features that can accommodate a ton of users and use cases.
As for the thread mentioned, the re-organization of the button bar/folders list was the part that was "under consideration." As we've made that change, I marked that thread as completed.