Looking for actual design answer, why does Zoe's bubble stay on the ground after it misses?

I'm not here to meme, or rant about how OP Zoe is, I'm here as a game designer hoping to find an actual game design answer. It seems to break so many rules for how League of Legends abilities are designed, what reason is there for it to linger for so long after missing? Heck I can understand if it did the "plop" at the end and then went away, but why make it linger? Surely this is power that could be moved to a better place on her kit?