Why is Co-op still the way it is?

Why is there not a more engaging co-op mode? What is the point in playing against other creeps? I'm sure they can think of something, look at ascension? What about a new map for 5v5s why is that still not a thing? Sure, they RECOLORED SR before but that isn't really anything special. Is summoners rift even a thing anymore in terms of the game's lore? So i'm sure the battle between champions doesn't NEED to take place there.