Well, to be fair traditional slings can also toss a ball into an outline, happens all the time.
Personally I think the magnetic slings are an awesome and innovative feature. What we saw in Sterns video was just a small taste of what the magnetic slings can do. Just wait until we see the magnetic slings in action, integrated with audio effects + DMD animations, and behave differently depending on the mode your in.
Traditional slings serve their purpose but its nice to finally see a unique and innovative feature that mixes things up. The magnetic slings will only enhance gameplay in unique ways and I think that will result in the game being more fun.
At todays crazy NIB prices features like magnetic slings are what I expect to see in a game. Traditional slings just toss the ball around in the same boring way over and over again, its time for something new. Magnetic slings certainly wouldn't be a good fit for every game but in a game such as Ghostbusters where they represent ghosts it makes sense.