I think it may be best for some to go back and read the book and watch cartoon before making the comments of how this and that don't fit.
Okay, I've read the book and seen the original Chuck Jones cartoon many times.
1. The Whos were never scared of the Grinch. That was the Jim Carrey Version and not in either the book or the cartoon. Also nothing suggests the Whos hated the Grinch. The Grinch disliked them for some reason.
Wrong. The Who's for all we know never even heard of the Grinch. And the Grinch wanted nothing to do with them until he stole Christmas. Him even strolling into town to "troll" people all Gru-like seems like a gigantic watering down of the character.
2. In the book and the cartoon, three of the reason he hates Christmas is because he hates Noise. (hints his hatred of Happy), he hates how they feast on the foods he dislikes (the grinch at the grocery store and his trolling), he hates the singing.
I think you're looking far too much into silly trailer gags for this reach, which is ironic considering you were yelling at us for even nitpicking the trailer itself.
3. The Grinch was a Hipster. He hated most thing mainstream and commercialization in general which was part of his hatred of them getting all their gifts and why he is shocked that he can't steal their Christmas just by taking their things. Makes sense why he would hate the song Happy as that song was mainstream.
I don't even know where to start with this one. Like, I just...
Look, you got the message right but the Grinch never hated the commercialization, he was merely a grump who was irritated by their festivities and loud candor because he didn't understand the pure spirit of Christmas. Once he learns that, he understands the representation of their joy and how much it matters.
That said: why would the song Happy exist, on the planet Who which in the Seussian realm is the size of a speck of dust floating around in the Jungle of Nool, and how would they know it's mainstream? Is there a Whovian version of Despicable Me and Pharrell Williams?
3. The cartoon is full of slapstick humor which is something Illumination excels at. (I.e in the Cartoon, the Grinch leaving the cave with Max to go over Christmas costs of Max and the Grinch breaking the 4th wall making visual gags of how Max tries to be cute while he doesn't want to be a reindeer and the Grinch being annoyed with Max and forcing him to act the role of the reindoor.)
This one we'll just have to agree to disagree, but I think Chuck Jones beats out Illumination's slapstick any day. It's smarter, has more clever timing and it also happens to be only 26 minutes long.