Each family of creatures has its own ‘theme’ which either consists of a particular ability or combination of abilities unique to that family. The Hadrosaurs get Superiority Strike + Greater Stunning, the raptors/dromeosaurs get Pounce, the stegosaurids get Thagomizer, the sauropods get Decelerating Impact/Rampage etc etc.
But, the ceratopsians don’t seem to have a particular signature ability or group of abilities. While all three natural ceratopsians (Einiosaurus, Triceratops and Sinoceratops) do get Greater Stunning Impact, Greater Stunning Impact is present on other creatures (e.g. Edmontosaurus, Iguanodon) and thus on its own isn’t a signature ability/combination of abilities.
However, with Decelerating Strike being provided to Sinoceratops in the 1.6 patch, I think it’s fitting to provide Einiosaurus and Triceratops with Decelerating Strike as their basic ability as well. Not only are they also ceratopsians, but they (like Sinocera) lost Minimal Stunning Strike for a basic Strike a couple updates back in the stun redesign. Oddly enough though, they didn’t gain Decelerating Strike like how Sinocera did last update despite their similar design and being from the same family of creatures.
This isn’t so much of a arena-balancing change but rather a consistency change to create a ‘family identity’ for the ceratopsians, so to speak. Maybe with the exception of Einiasuchus, I doubt that Einio/Tricera’s hybrids/superhybrids really need or want Decelerating Strike, so I don’t think it’s necessary for their hybrids/superhybrids to inherit Decelerating Strike per se.
Now, if only we could redesign Paramoloch and Tuora with domed heads so they can inherit Shielding Strike…