One shoudl be able to export products, make changes in a spreadsheet and impport all the products back with all the changes. This shoudl be a basic feature of an e-commerce. It is very impractical to have to manually update every item. If you have 1000 products, just to make a promotional price change, you need to spend hours making manual changes. Use the handle as a reference and update just the fields that are on the import sheet. Leave the rest of the data as is not to delete all the data that was not possible export. It shoudl not be very difficult.