Yeah, it sucks things up. But the people did not die. It doesn't kill. Does that mean it's dangerous? Let's find out.
So, we thought for 3 episodes that the Wither Storm was dangerous. Before episode 3, we thought everyone who was eaten died. But they didn't.
The Wither Storm's biggest weakness is the Command Block. Jesse, the Gang and the Order know that, but everyone else didn't. The gang could easily get sucked up on purpose, then attack the Wither Storm from the inside.
So, today, I have come to the conclusion that the Wither Storm is not dangerous. Yes, it looks scary and sucks things up, but it can easily be destroyed. The threat is the Command Block, NOT the Storm.
EDIT: Adding on to the theory, I believe Jesse's Gang will convince Ivor to make another Elixir, then they will do everything above and destroy the Command Block.