I think it's an interesting refutation to Google's "one search box to rule them all" philosophy. Over the course of Windows Vista through 8.1 Microsoft attempted just that at a consumer scale that Google could only wish they could impact "where they live". (As much as people assume people live in the browser, Windows is still Windows.) The evidence mounted up overwhelmingly that people didn't want just one search box, that Google is wrong (they've yet to unify their search boxes like they claim to philosophically anyway), and that the context of where a search box appears matters, and so Windows 10 has seen the re-separation of search boxes.

One of those "context" switches that Microsoft finds is a useful context to know is "power user" versus "regular user": regular user Start Menu versus power user Win+X, regular user Search and Run versus power user Win+R/PowerTopys Run. (At one point in Windows 8 Microsoft tried to use the Win+R shortcut for something that wasn't "power user run a thing" and nearly saw a revolt.) It becomes a self-selecting "reveal" of different feature sets to match what features the user thinks they are ready for.