Why do Zombies run in movies now days?

I prefer zombies from the George A. Romero movies. They don't run. Zombies can't run, it's a simple fact of what happens to the human body after death. It's alittle thing called Rigor Mortis, the body's joints, muscles, it all stiffens up. Makes it impossible for zombies to run. At the most they can fast walk or shuffle. Besides running zombies aren't scary. The overbearing numbers of the walkers is what's truly scary.