Actually, to do with the fact size matters...
I was trying to help someone on a thread in Geeky Stuff and find that the image display really lets things down - as the images are kept small.
Given MN expects a browser window on a desktop to handle 1024 pixels in width (or thereabouts), why can't the image be around 98% of the width.
I've no idea what you do on mobile browsers wrt images but clearly they'd have some problems with very large images... but 98% of 'window size' could still work, surely.