I'm just a simple person with limited knowledge and skills, using WP for a holiday rental website and a charity website with illustrative photos. So I too miss the ability to add padding etc. to images in pages and posts. Yes I have only just noticed it is no longer possible in the edit images options, but it's a static site, I don't update it every day.
I thought WP was supposed to be for everyone, not just developers and pros. But now I need to search Support to find out what happened to this feature, how to overcome it, and learn why these simple features were considered not sufficiently useful to be dumped in an upgrade - how do you figure that anyway? Nobody asked me.
It may seem easy stuff to most of you guys out there but why should I need a plugin or to edit html or CSS for a perfectly simple useful basic function for editing and positioning an image.