This is the same reason that we still practice the most basic moves in our dojo - front and back punches. In multiple years as a martial artist I've rarely employed anything beyond basic moves in a sparring match because they tend to open ME up more than my opponent. I'm a big guy. I don't need to do some kind of flying-jump-hammer-of-death-twisting-sythe kick to win. A simple, straight front snap kick will do nicely. :-)
My experience with the Forms is far more limited, but from my experience thus far someone employing Shi Cho with precision, power and clarity should be able to win against a Juyo or Niman user who is not as well grounded in those same basics. That being said, learn those basics and keep them fresh. My view of Niman and Juyo is that they are both "free" forms - using the bits and pieces the combatant has picked up from the other forms and melding them into a form all his own, allowing him or her to be highly adaptive and less predictable.
Which is why, when I DO that crazy spin kick, my opponent isn't ready for it. :-) That's MY goal with the forms: basics, basics, basics, BOOM.
But first I have to learn those basics. so ... Shii Cho.
Well said, Karm
Reminds me of a Bruce Lee quote: "I fear not the man who has practiced 10,000 kicks once, but I fear the man who has practiced one kick 10,000 times."