In my home game, non-malignant, non-magical chimeric gryphs (like Owlbears, Griffons, Hippogriffs, Winged Snakes, Polar Bear Dogs, Turtleducks, and the like) are Beasts, not Monstrosities.
Same, and I suspect that quite a few folks home-brew the class this way. And obviously we see it in the D&D movie, so clearly the writers were like "It's a D&D movie - why can't the beast be an owl bear, because that is way cool?". I think WotC needs to acknowledge that there is a big difference between a displacer
beast and a Yuan Ti Abomination. In the magical D&D world, some beasts are a little funkier than in ours.
Letting moon druids have access to beast-like monstrosities would solve the perennial problem that they run out of options as they level up. Plus, it's way more fun.
And...let's face it, moon druids are getting some form of nerf - specifically to their insanely high potential HP pool. Plus losing elemental forms, which make no thematic sense but really buoy the subclass up at the middle levels. Nerfs
suck. But giving them access to the thing a lot of folks
really want, beast-like monstrosities, would go a long way to make that better, especially if the mechanics are implemented to keep those shapes competitive all the way to top levels.
Give up on most of the moonbeam stuff. Yes, we get it, Moon Druid/moonbeam. It's a motif. But it's just not very fun. Not fun like wildshaping into an owlbear and ripping someone's face off. Give the people what they want.
Edit: I'm going to add a list of beast-like monstrosities that are already in the official rules and that I think Moon Druids should get access to, or at least to a curated list chosen from.