It's not that the file isn't useful. It is - especially if you're bulk editing a bunch of files. But if you're using it for a backup, you're going to be sorely disappointed if something happens to your store.
For starters, the file doesn't have any information about your collections. If your products are deleted, and you've created custom collections, importing the product CSV file won't put the products back into the proper collection. Rewind, our backup app for Shopify, handles custom collections without any problems.
Secondly, and perhaps most importantly, are product images.
When a product is deleted from Shopify, the product images are deleted as well. If you try and import a CSV file after your products have been deleted none of the images will be saved, and you'll spend hours or days manually adding the images back to each of your products.
Here's a quote from one of our customers who ran into this very issue:
The next thing that occurred in the last year was when we accidentally deleted a product collection containing approx. 75 sku’s. At first I thought, no big deal, I will just import the product_export file from Shopify that we had downloaded each month and we would be back up and running. Well, that was not the case. If you have ever tried to bulk import the product file with data into Shopify you know the challenge.
Lastly, for stores with UTF characters in their products, exporting and importing the CSV file often results in incorrect or missing characters being inserted into products.
Shopify is a great e-commerce platform - one of our favourites. There are tons of great features available for Shopify merchants. However, if you're using the product CSV file as a backup tool, you should probably think of another backup solution to make sure you're fully protected.