The Chinese have a name for the "single advancing" or "arrow" step in Wing Tsun. I don't have the Chinese transliteration handy right now, but they call it the "One Step No Kicks" step. It's a very apt description.
Kicks need distance to work. Kickers need distance to kick. If you as a WT fighter take that distance away from them, they can't kick you, period. It's really that simple. This also relates to the concept of "sticking". Once you have quickly covered the distance between you and your opponent, you "stick" by using your advancing steps to keep following him wherever he goes while constantly invading his stance with your front leg.
The first part of this idea is perfectly demonstrated by this video clip from a WT guy in Argentina, I think. Watch his opponent jump and spin around like a mighty whirlwind - but when it's time to engage, you suddenly see a very different picture. (What happens after that on the ground isn't that relevant here, but it is also a form of "sticking") Watch this:
How many kicks did you see the kicker throw after the fight started? Zero. He never had a chance. No room. Hence, the Chinese name for the step.
Also consider the size difference between the two fighters here. The kick boxer in the red jacket probably outweighs the Wing Tsun guy by fifteen to twenty pounds. Another piece of evidence that Wing Tsun is indeed a great "equalizer" in self defense.
When you practice your footwork from now on, especially when practicing your arrow step, remember this video!