I think its mostly priority, for example, if you securing an Ocean Drake as your 3rd drake while the enemy team is getting a tower thats a no go. Ocean drake is less useful the longer the game goes on(for most champions) so a trade like that would mean a commentator says "Why, that's pointless."
Cloud drake i do think is more useful in Pro play because extra movement speed is amazing but again if your team is losing a tower for such a low amount of movement speed it's not worth it because you lose map pressure anyway.
Cloud Drake: If you losing map pressure for a dragon that's supposed to help you apply more, that's a no go.
Ocean Drake: If your losing anything for a drake that's only really useful in the first 20 minutes, it's a no go.
Earth and Fire dragon are always useful though, you can never go wrong with more damage. In my opinion, Ocean and Cloud should spawn more frequently early, as in have a higher chance so instead of a random chance you have a higher chance of Ocean or Cloud in early but lower chance late game. That way their usefulness can be fully expressed even in Pro play.