Best thing about this event is undoubtedly the dialogue lines where Rex himself bashes the Dinosaur type in favour of others (Dragons mostly). It seems that Dinosaurs in Yu-Gi-Oh! are either straight trash or broken as all hell (if I'm not mistaken Dino is meta currently in the TCG)
The sad thing about this is that Konami knows how bad Dinos are in the current version of this game. And they don't improve them with Rex' rewards. I think they'll add some massive new Dinos in the next big box, so you'll have to pay to build a new meta dino deck with some new UR Dino monster cards and supports.
Ulle, you are right. Dinos, and Fairies for 🔥 sake, are the types that have been receiving the middle finger since a long time. Regarding the new box thing: I wouldn't be surprised; Elegant Mai event: Ice Barrier Princess released in the same week the Ice Barrier archetype was available in the box