[[File:Example.jpg|thumb]] is great for the normal kinds of images that you would use in an encyclopedia article. It's really lousy if your goal is to put up a full-width screenshot or a panoramic photo.

I want to be able to do this: [[File:Example.jpg|frameless|center|80%]] or this: [[File:Example.jpg|thumb|90%|Caption here]]. My goal is having images like the screenshot at https://www.mediawiki.org/wiki/VisualEditor/Special_characters to fit the reader's screen, rather than my own.