Bipedal locomotion is tricky. Unless you have those big instep "toes" like you see on old windup toys, you can't center weight over both feet, which means you have to shift weight between each step. Humans walk dynamically, once we start moving we're basically in a controlled fall from one step to the next, constantly catching ourselves. This is only possible because we're constantly monitoring our balance. This is a mental coordination we've developed, as a species, over thousands of generations and, as individuals, over years of practice. The downside is that if something happens mid-walk to interrupt that coordination, we're almost guaranteed to fall.
Robots are expensive, falls damage that expensive equipment. And rather than countless generations of refinement, they have to develop their coordination from deliberate programming. The "where's the bathroom" walk is much slower than human walking, but it's fairly stable and predictable; balance is fully shifted to the planted foot before the other lifts from the ground. A lapse in coordination won't send the walker face first into the dirt.
Eventually, robots will have sufficiently sophisticated autonomy and "reflexes" to be able to throw themselves into a controlled fall. But for now, the bathroom walk is fast enough for most applications, while being safe enough to avoid fall damage.
