Why the push for WebP? Does it REALLY save that much bandwidth? Unless it can be shown that WebP has SUBSTANTIAL advantages over other image formats, then let the site owner decide what format they want to use.

Finally, what about photographers and artists that want their images in a specific format for a good reason? Are you going to force them to use WebP?

This seems like a really ill-conceived idea that appears to be pushed by contributors with a vested interest in seeing WebP adoption increase (i.e., Google). It isn’t the place of WordPress to push adoption of a proprietary image format of one of the world’s largest corporations.