Are there any benefits of having all the pictures in the sitemap? Are there any disadvantages of a huge sitemap.xml file? I am using Softplus GSitecrawler to generate my sitemap and there's an option to include or exclude pictures, movies, pdf's and so on. I have many pictures on my site and including them in a sitemap, makes it over 1MB in size. Excluding them, the sitemap.xml is around 40KB (if I recall correctly).
IMO you should include some pictures but not all. For example the first picture of each gallery. Also maybe you should give lower priority (0.1) to pictures.