AFAIK it is a "feature" that has been in there since before I started using it 18 months ago, so there is no way you would want to go that far backwards. If you really care, just run Calibre from source and change the code to do what you want.
Personally I never use metadata from the file, it is so inconsistently rubbish I prefer to use the metadata downloads to fetch it instead. Keep a few different file name regexes (for permutations of "title - author" vs "author - title"), toggle between them with a keyboard shortcut via the Quick Preferences plugin works for me.
There is a feature request floating around for more granular control when adding books of exactly what fields it should import. However it is not on an actual todo list, no doubt it will happen "one day".