I think if Microsoft had made an easier bridge, faster from Win32 to things like Live Tiles (and the Charms, too) there would have been a lot more people praising the Live Tiles today (and maybe even the Charms). Live Tiles really made their case on Windows Phone 8 where nearly every app supported them (relatively well), that was the only "Notification Center" for missed notifications, and its glanceability became very obvious.

Charms are somewhat similar, too. On iPhone almost every app needs a Share button somewhere and almost every app still has it in a different place today. On Windows Phone 8 it was much more obvious why a dedicated OS-level Share button accessible just about anywhere in any app was pretty great. On Desktop it wasn't seen as helpful as almost no apps supported it (either as shareable things or as apps that could be shared to) because there was no easy Win32 bridge and Microsoft also didn't think to try to integrate with clipboard operations until too late in Windows 8.1 (and then never quite delivered it because most everyone had already written off the Charms by then), as what could have been a potentially easy path to use the existing Windows "share paradigm" to bootstrap.

(You can make cases for the other 4 Charms as well beyond the Share charm, but the Share charm is the most obvious where Windows Phone proved it was a good idea but the Desktop didn't have enough supporting apps to also prove it there.)