Making a vet change a default if he decides he doesn't like a change upon upgrading won't drive him away, but Emacs' unfriendly defaults are always driving away noobs. Therefore Org's defaults should be noob-friendly, not vet-friendly.
Probably vets should use legible settings as well. I became accustomed to less-legible Org settings, and thought they were superior. But when I cleaned up my Spacemacs config, I incidentally restored some default legibility tweaks I'd disabled. After a brief exposure, I realized the tweaks were superior, and that my preferences had been wrong. Changing the defaults can overcome vet inertia and improve their UI.
> Terminals can display colors, underlines, italics, and bold text
Proposed legibility changes don't affect those font aspects.