Pyke has a lot of wasted opportunity

Why put so much emphasis on a list of those who betrayed him if it's nowhere in his kit? Why isn't the leviathan apart of his ulti? Wouldn't it be cool if Pyke was able to apply debuffs and enable his allies to blow up an enemy instead of just having some CC? Why doesn't he dive underwater with his W? Why does his W do practically nothing? Don't get me wrong, Pyke is an insanely cool champion and is very unique, However, I feel as though there was a lot that could have been done with his kit that wasn't really delivered in the end.