Since the worldview that characterizes the thinking of our elites holds that there are no evil people in the world, only the victims of oppression by the rich and powerful, we must have an explanation of how the Grinch became the misanthropic who-hating anti-Christmas activist that the original book presented to us without explanation.
It turns out that the Grinch was ridiculed by as a child by the man who is the current Mayor of Whoville. The Mayor is a rich man whom we see mistreating the man who shines his shoes and so must be the real villain. The boy who would become the Mayor torments the Grinch and ridicules him for having hair on his face while still in grade-school. The Grinch tries to shave himself and ends up cutting himself for which he is ridiculed even more. This happens during the Christmas season and so the Grinch combines his hatred of Whos with a hatred of Christmas.
During the main action of the story the little girl proposes the Grinch for the prize and quotes the who-rule book against the Mayor that Whos must 'treat everyone the same, no matter how different or strange' (quoting from memory), making the issue prejudice against those who are different, of course. The little girl's plans to bring the Grinch back into the fold of Whoville by making him Cheer-miester for Christmas is foiled by the Mayor who manages to insinuate reminders of the Grinch's childhood humiliations into the award ceremony, triggering the Grinch's rampage which ends with an explosion destroying the Christmas festivities. Amidst the rubble in the aftermath of the Grinch's rampage the Mayor declares that they must get back to "Christmas as it should be--Grinchless!"
In the end the Grinch decides to give Christmas back pretty much as in the book.
So instead of a story about a curmudgeon whose heart is changed by the Christmas spirit we get a morality tale about the the evils of rich and powerful and the harm of prejudice against people who look different from us.