Hi,
Thanks for your input. We can potentially add a hidden option to deactivate the deleting of the images.
The disadvantages of not deleting images can be quite big. Specially for people with not a lot of space on their hosting (and it happens a lot and that's why several people asked us to delete the images when the products were deleted).
In fact, just recently, someone asked us to even delete the images from the custom fields (which is not done yet as it is more complex to do).
So really, it depends on where you stand.