More research against it as a pre-exercise "warm up" - but I feel like I'm facing down a chorus of folks in dogi and hakama singing "Tradition!"
"More fundamentally, the results underscore the importance of not prepping for exercise by stretching, he said. "We can now say for sure that static stretching alone is not recommended as an appropriate form of warm-up," he said. "A warm-up should improve performance," he pointed out, not worsen it.
A better choice, he continued, is to warm-up dynamically, by moving the muscles that will be called upon in your workout. Jumping jacks and toy-soldier-like high leg kicks, for instance, prepare muscles for additional exercise better than stretching. As an unscientific side benefit, they can also be fun."
or of course general aikido movement exercises...