Well, for one to illustrate the page on the story itself. There are barely any images on that page, and I see no reason not to want to add images to it.
Plus, it has some of the best close-ups of these actors we could possibly get in the 90s. You won't get a better close up of Colin Baker in his half-fit-half-not-fit stage then in this story. Then there's Peter, who gets a lot of good close-ups in this story while he was still in his prime; as well as Sylvester and Pertwee.
Plus there's the images that could go in behind-the-scenes sections, like the Brig meeting 6 or Peri and Nyssa being on screen together, both notable things that had never happened on screen before... I could imagine adding an image from the story into the behind-the-scenes section of the Fourth Doctor's page, for instance. Then there are all of the pages about things in the story; like The Rani's menagerie or Gita Kapoor... There's an infinite number of pages that could use images from this story, really.