The increasing flatness and colour dullness of each version of Mac and Windows OS since the latter half of the 2000s (from the Vista/Leopard era) has, for me, correlated with a general decrease in the feel of "magic" looking at a computer.
Windows XP was bright and optimistic; Aqua was a breath of fresh air; both sides came from dull grey UIs. 20 years on, it feels like we've returned to the greyness of the 1990s.
Perhaps in 2021, to mark 20 years, we could have some developments on the desktop side that justify a return to a more optimistic UI, that make me (us?) feel the "magic" again.
Or maybe this is just a more general nostalgia.