This is a bit confusing. Your comments are factually incorrect (there are no forced-full-screen apps in Windows 10, and the default PDF reader is Edge, which is windowed by default and was designed from the ground up for Windows 10, never for Windows 8 or "Metro"), or at least outdated.
It's a bit of a blemish that there are two control panels, but almost no users are ever exposed to Win32. You can do virtually everything (from updates to domain join to adding/removing Windows components) from the modern Settings app. The legacy control panel is just that, and is irrelevant for most users. I'd love to see it modernized, but there are many much better uses of resources (security! performance! battery life!) than modernizing 90s-era utilities that few customers are ever exposed to.
It's a bit of a blemish that there are two control panels, but almost no users are ever exposed to Win32. You can do virtually everything (from updates to domain join to adding/removing Windows components) from the modern Settings app. The legacy control panel is just that, and is irrelevant for most users. I'd love to see it modernized, but there are many much better uses of resources (security! performance! battery life!) than modernizing 90s-era utilities that few customers are ever exposed to.