I see the other side of it, too. Most of those "kung fu master fights MMA fighter" videos feature someone who has honed the perfect technique, but never sparred, and as soon as he takes one hit he's basically done for. I don't know if it's that he's never actually been punched or if its that he is shocked his perfect technique let an attack through, but after that it quickly becomes a TKO.
Should you need to defend yourself, I think part of martial arts training is getting used to taking a hit or two and keeping your wits about you.
The other thing is that pain is a powerful teacher. I'm not advocating for brain injury, but if you're sparring, you learn how to avoid hits because you generally don't want to get hit. Another thing that could be important should you need to defend yourself.