This is a good point. The book certainly didn't feel that way. The problem is that for the Hobbit movies, Jackson started with the original material and then decided to overdo everything about 5x beyond how Tolkien wrote it. So they can't just ride in barrels down a river - an incredibly perilous thing to begin with.
Here's how I picture Jackson deciding to "improve on" the original. They can't just ride in barrels, they have to ride in inexplicably stable barrels that don't take in water, down a river with some crazy fucking rapids, yeah!, while
You know that if Tolkien sees this he'd be like "Duh, I totally should have written it that way to begin with, it's waay more radical and gnarly!"