This is of course ideal for a plugin. It would be great if the core team takes care of the plugin (like e.g. Sketch, Mailchimp and many others do as well).
It’s also a perfect marketing tool in my eyes and is great to promote on the website and also on Unsplash’s website there are countless integrations listed. (https://unsplash.com/developers)
Let’s wait and see if anyone is interested at all. If someone wants to implement it as a plugin, I’m happy to help.