How about dark mode in macOS Mojave? I mean, yeah, third-party apps need to be coded to take advantage of it. But it doesn't mean there can't be a dark mode 'the easy way': I'd be happy if Apple were to bring dark mode just to the native apps (e.g. settings, messages, mail, phone, calendar, Safari etc.).Dark mode implementation requires heavy lifting from app developers to ensure the color palette works on each app. Unlike panorama, dark mode isn't something Apple can work on behind the scenes and flip on suddenly.
If Apple wanted dark mode, they would have announced it during WWDC where millions of developers were tuned in.
As far as third-party apps: just like with every single year and every single major-update, developers need to update their apps to take advantage of certain features. That's in no way different than how it'd be with dark mode.