Peter 28Oct13: I really believe that there is a truly fundamental difference between native format (Projects in Audacity's case) and non-native formats (i.e. audio files) and we need to respect and observe this distinction and make it as clear as possible for our users. Only Projects should be capable of being Opened and Saved and audio files should only be capable of being imported or exported. Simple, straightforward, accurate - "does what it says on the tin"
We do not and cannot work directly on any audio file (WAV, MP3, whatever) so for my money this means that users should not be able to "Open" such non-native format files. When all's said and done Audacity is *not* opening an audio file for editing. Rather when the user invokes the current "Open WAV" command what Audacity is doing is a) Opening a new Audacity project and b) then Importing the audio file. I do not like this at all (in fact I hate it) because it hides the import from the user and leads them falsely into thinking that we are operating directly on an audio file: Open <audio file>, edit <audio file>, Save <audio File> - it ain't like that, it really isn't.
Peter 31Oct13: I note from the existing proposal that it states clearly on the main page: "'Open' will be renamed 'Open Project' and ONLY open an Audacity project.".
and on the Talk page Gale wrote on 26Apr2011: "Yes but we are all agreed I think to restrict File > Open to projects. "
So we do seem to have consensus, and mostly always have had, on the basic underlying precept here.
Steve 3Nov13: I'm sure there will be some complaints [from some] users because it is a change, but the weight of argument (from everyone) for why this is the right thing to do is overwhelming.