First, if you desire a feature then you should ask for it. However, it is unlikely that a new feature will be implemented unless you can convince developers that it is a good thing.
The problem with your feature request, as I see it, is that you have asked for a fundamental change in the definition of raster image formats. You also want to incorporate layout program features into an image editing program.
I understand what you want but my point is that you can achieve what you want by either (a) creating multiple different images from a single base image; (b) submitting a single larger image and letting the editor crop as he or she will; or (c) using a layout program that allows you to crop images to fit into frames.
[Sorry, Pat has replied while I was typing. I agree with you, Pat.]