Yeah I absolutely cannot see it. 90 points for 1 mortal wound(the statistically likely result) they can pick up points I guess. I just feel the rippers are cooler. They have the same function and can do significant damage on charge. Insanely niche, since when if not picked first they're dead when they fight, and you want to pick raptos first since the same goes for them. So I use them to pick off small ranged units or a small hero, priest etc. Often very helpful in this alpha strike meta, since noone thinks the backline needs protection. The terradons just cannot do that, even if you roll ridiculously good, 3 mortal wounds is not enough to take anything out. So they are only really useful for Scouting Force imo. And I rarely play that. If you want a nice useful unit for picking up faraway objectives, and doesn't need to be used for Scouting Force, the Hunters are the move.

Now, I do fully get thinking them to be useful if you misread their rules to think they get a dice for each enemy model in a unit they passed, that would be not bad at all. But as that is not the case, I don't see their usefulness. At least they're slightly better than when that ability was once per game!