This would help massively with automation of workflow, as currently you have to write additional queries to filter out some answers that are long gone from the forms, but are still present in every export. I have an answer that was added by mistake by my predecessor and I have no idea what it even means. It is not present in the forms anyone, the date filters are set to long after it was deleted, but a column for this answer is still being created. Deleting case properties is something that was asked for long before me too.
Same goes for user properties, this is just unintelligible.
In addition to this you should be able to select which exact answers you want to see in your export after expanding a question.