I upvote for this request:
This is needed by all our clients, on some pages, it's total overhead loading the same image multilple times.
I haven't seen this feature in any other shopping cart.
How do you suggest it will look like, can you describe your idea in more detail or show an example where this is implemented?
As an option for you now is to create a dummy product with common set properties and uploaded pictures, then use the "Copy product" feature and copy it to the real products.