Images often make up the largest part of webpages.
They have their own tab on Google results and even their own algorithm. Appearing in image results should be part of a complete SEO strategy to reach users looking for images.
Your content should contain high-quality images either way, so why not optimize them too?
It’s like the search engines are giving away Oreos and milk for free. Don’t only take the Oreo – it’s way better dunked in milk.