I understand that not all features can be accommodated. However, as a non-programmer it is hard for me to know what features will be easy to implement and which ones will have a "huge overhead" so rather than self-censoring I feel it is best to suggest the feature and leave it up the the developers whether or not they wish to implement it.
Moreover, in my feature requests I always try to provide a concrete example of how I would use the new feature, as I do above. I make these suggestions when I encounter a problem in my now daily use of the app, and the above example is not hypothetical but something that actually happened to me when I received a number of papers for a conference and find myself needing to edit the metadata for each one individually.
It would also be useful in correcting mistakes in metadata across multiple chapters from the same edited volume, or multiple items from an author whose name requires an accent but where there is no accent in the automatically added metadata. Since Google Scholar is full of incorrect metadata, there are actually many situations where this could occur.
I should also add that most database-style apps I have used on the Mac, including iTunes, Bookends, Sente, etc. have this feature (bulk editing). Click multiple iTunes entries, Sente references, etc. and the standard edit field comes up, but changes are propagated to all checked items, rather than just one.