This did not just simply come randomly, however. Players have been demanding and asking for World of Warcraft Classic for many years now. And Blizzard has likely learned from companies like Jagex that regained a huge portion of their player-base with the launch of Old School RuneScape, which prior to it had a 2006Scape private server. Similarly, World of Warcraft Classic/Vanilla has been around in the form of private servers for many years now and has been very popular. Even top players and streamers have been known to play on these private servers. The only issue is Blizzard were not the ones profiting from these ventures.
Hey kid… You want unlimited power? Buy now at the low-low-low-low-low price of your eternal soul ^(and the destruction of your entire planet, ruin of your culture and its way of life), but hey, don’t worry about that. Just think about those guys who called you names at Shaman school, think about the elders who cast you out, and think about the 15 foot tall burning infernal crushing their proportionally tiny skull between its… Do rocks have fingers? Who cares kid, just think of the power.
That's not to say that everyone has an unrealistic vision of what vanilla WoW was like. There were already plenty of people on the WoW Classic forums pointing out that perceived bugs are just recreations of the original game. And as noted before, a flaw to one player is a key component of the original positive experience to another. WoW Classic will surely please plenty of purists in spades. But this goes to show that it won't be for everyone who has fond memories of the game circa 2006.