While the big, noodly, stretched-out humans look horrifying when they're still in the holes, just try to think about what they'll be like when they get out. Big, floopy things that can't walk, so they just fall flat on their face and twitch around.
Unless they actually can walk. In that case, it's absolutely horrifying.
The horror doesn't really come from the idea that they might have somehow become dangerous. It comes from the fact that they used to be normal people, and now they've been twisted and contorted into nightmarish shapes while still alive. So, it doesn't really improve if they can't move much after coming out. If anything, it just turns into an example of And I Must Scream. Of course if they can move, they might be able to play a mad game of DDR◊.
The holes were even shaped to accommodate people's hair!
"Si-sir! It's slowly coming this way!"
"Th-this [X]! It was meant for me!" along with GASHUNK, "DRR... DRR... DRR..." and "It's slowly coming this way!" have all become memes, despite the fact that their source material is meant to be anything but intentionally humorous.