Yeah I found all the threads, and it looks like others are suggesting this plugin: https://wordpress.org/plugins/advanced-image-styles/
Still, this is a terribly newbie unfriendly change to the editor and I don't know why anyone thought it was a good idea. I've been a faithful advocate of WordPress for going on 10 years, in part because of its ease of use for non-tech folks. Relegating these kinds of things to plugins or CSS only makes it more difficult for non-developers to use the platform.
Thanks for your reply in any case, Andrew, appreciate the speedy response.