Hmm, I disagree on this one... Most of the team, you're likely to switch images per theme anyway, because your logo is just not in the right dimensions or (background) colours.
That's the thing, most sites don't run multiple themes, and of those that do, most of the time the admins don't really seem to care anyway and just use whatever logo they have.
A lot of themes don't even adhere to this one anyway, especially ones that come with their own logo, because people end up being told to replace the image rather than update this setting - because it's set in the theme's CSS more often than not. Certainly this is true of a bunch of Crip's themes, most of the DzinerStudio themes and some of Bloc's themes.
I'm aboard the discard boat, myself.
I have no qualms about removal really.
Well, they're all theme-related options ... If they're not consistent throughout all themes, they have no place in $settings, if you ask me. But I gather you're planning to change all that.
That's the thing. You and I might see them having per-theme use but experience of what 'real users' do (since I doubt you and I are particularly representative of the bulk of users) seems to suggest that themes don't tend to worry about these things much, doing what they do their own way, and dealing with it later, assuming of course that users 1) run multiple themes and 2) want to have different settings for each theme. The first is uncommon, the second rare at best.