Tbh the tiers don’t matter nor make sense. Several dinos are in the “wrong” tier. I think the reason why is that they need the “fan favorites” to be on all tiers, otherwise you’d start out with dinos you might not know, like the Majungasaurus, and you’d have to grind to get all the known dinos, which in turn might push away JP/W fans.
Whereas starting with a Trike will be the hook of the game, and that’s another reason why you get a t-rex at I believe lvl 30.
So meh, I don’t think it matters nor do I think they’ll do it, since we’re already like 4 years into this game and nothing substantial has happened with the tiers of dinos.