I meant it is certainly NOT difficult to include. (I need a proofreader)
What are the missing features out of interest?
Marcus, Just read the rest of the forum. It's full of questions like... "where is this feature?" And full of answers like... "That won't be ready for the commercial release... but we plan to include it in an update." I'm not going to try to list it all when it's all there already.
You'll have to take my expertise at face value, but I can assure you that exporters and importers are quite different beasts. It's entirely plausible that it's relatively easy to modify the existing Win32 codebase to export to a new format, but trying to add an importer for legacy formats to a brand new codebase is a different task altogether. I fully agree that backwards compatibility becomes much more of a dealbreaker when it's also a matter of cross-platform compatibility, but it's not likely to be a trivial task. Remember, the CEP codebase is going on a decade-and-a-half.
On the subject of missing features, again, I cannot but appeal to your trust here, but I ensure you that with a brand-spanking new codebase, the last thing you want is feature creep. One wrongful step, and the stability and longevity of the code is in jeopardy. If Adobe is trying to revitalize Audition as a heavy-duty sound design and DAW application ("Photoshop for sound"), the importance of code stability cannot be overemphasized.
Now, for the users, this shouldn't really matter -- we want good features, and we want them now. All I'm saying is, I can understand why Adobe has chosen this direction. It could be argued that they should have held Au4 under wraps until it was more feature-compatible with Au3, but really, what's the point of that? If it's usable now, why not just get it out the door, and let the community provide feedback on what's missing? It's how most other software companies tend to work, and I for one enjoy being part of the discussion.