Again, I have had some time to catch up on the blog world, and have enjoyed much of the writing Mladen Jovanovic, a performance coach from Belgrade, Serbia at his site, Complementary Training. One of his recent posts discusses the 'false step' or as some call it the "plyo step". He does a good job of presenting the movement here; Is taking a false step a bad idea?
As Mladen said, context is exactly right. If it's speed, then whatever it takes to effectively position the body to apply the optimal forces. If it's technical, then we have to be smarter about taking away an instinctive movement, and coach what is necessary to ready the body for the next necessary position; not just control something because we, as coaches, like to have control.
Loosely related, but more closer than one might think, the startle response/reflex/flinch (whatever one wants to call it) gives some insight into what happens when in a split second we need to make a response to do something as fast as possible. NOT false stepping, in a speed dependent context, is going to be a conscious decision thus slowing the decision and movement process; in terms of neurological processes, there is a great lag time between an unconscious decision to a conscious one (even to the point of recent research questioning the idea of what we know as 'free will'). A false/plyo step essentially is an unconscious process which enhances speed of every aspect of the movement.
This is a good video on some aspects of the startle reflex from Tony Blauer, of Blauer Tactical Systems, a specialist in close quarter tactics and different scenario-based training for law enforcement, military and self-defense instructors. Obviously this is regarding close quarters combat, but what would be a startle response of a human running from or towards an emergency? Sometimes it's important to allow instinctive responses to do their magic and to not tinker with something that has worked for a very long time. Use the instincts to enhance performance.
A moral to the story is that it's not necessary to control everything an athlete does; we're not working with robots and the body has some seriously effective wisdom inside when allowed to do its thing.