25mb is way over the image size limit, you should try resizing it, optimizing it, and potentially converting it to a JPG. The upload dialog should show max size you can upload. It sounds like the error message isn't appearing when you try to break the limit though. I'll file a bug internally. Thanks
For layout images, no we won't have this. By hosting the files ourselves we ensure that they will never go down and break the page, and people follow the size requirements to help prevent negative impact to page loading. (In this example, having a 30mb image load every time someone loads the page is very excessive, so I think the rules about size are doing their job)
