Our thinking is that thumbnail generation of media images should always be based on the option max height set on the local machine. It makes sense to create the thumbnails when the image is loaded, or when the service is loaded to avoid resizing images on the fly. I think @AndrewArm and I are talking about a different class of image -- not thumbnails, but remote images. Small thumbnails make sense for the UI, but not the remote.
I recognize that we are really asking for a new feature altogether.
I'm wondering if we should change the way we prepare services at our church, and make them each Sunday morning, based on text from our bulletin and images and other media from a dropBox folder prepared during the week. It's usually only a 5 minute task for us, since we have almost all the hymns already in the song database. Or perhaps as Andrew suggests, just reload all of the images (if that works).