The problem with keeping both methods of attaching recordings on the song edit page (uploading from there, or selecting from among recordings uploaded from the Recordings page) is that the function would then become more complicated than it needs to be for the most common use case. Someone starting from the song edit page is likely to be confused by the option to select from among existing recordings ("why would I want to go to a different page to upload the recording, when I could just upload it right here?").
Giving you a chance to rename or manually attach the batch-uploaded recordings after they have been uploaded would be quite complicated, and I don't think would be a good value for most users (i.e., spending that time on other updates would be more useful).
I still think that if you don't want to take the approach of matching up your filenames on your computer before uploading, then you could just upload one at a time from the song edit pages, which is very similar to the old workflow, the difference being that you have to wait for each file to upload when saving. That doesn't take very long when you're just uploading a single file.
Anyway, I'm sorry you don't like the new setup. It is based on lots of feedback about the old setup, and so far most feedback about the new setup has been positive. But if more feedback warrants another change, I'll do that.