That change replaced the original full size images (1200x1600 pixels in a random sampling of the links) with the large thumbnails of each image (375x500 pixels for the same image), which means that they no longer overwhelm the page. It also added click-through links to the full size images.
This is a worthwhile edit because it makes each image more manageable, especially on mobile devices which may not have high resolution screens.
It also reduces the amount of data that must be downloaded to view the page, another benefit for mobile devices which often have data caps, or for people with slow internet connections.
Please approve edits like this in future.