Meh, i didn't even bother to play it actually, the "novelty" ends after bans and picks, it's kinda like play on the day of the opposite.
The map was still the same, the champs had nothing new to interact with, it's just the same game just with different champs.
Game modes are needed to add something that usually in a normal game you won't find (Doom bots, U.R.F., One For All ....).
I didn't play Poro king that much either, there was something but it wasn't enough for me.
And OP is right, they made such a "simple" game mode to just record feedback to see which champs are the least wanted\least played;
Which is extremely good in my opinion, it shows that they possibly care to make every champion desirable to play, because in this game there's too many people that pick a champion not because they like them, but because they heard he\she\it's OP.