i had posted a blog following the finale concerning why i felt the dharma initiative was important after all here:
to follow on that train of thought... if the DI knew about the source's abilities in relation to the human consciousness, then it only follows that the others must have known as well. this is why walt was so important to the others. they knew about his own abilities to hill things into existence (birds, polar bears, secret messages on computers, etc.) and may have believed that he could have been trained to focus these abilities to achieve exactly what the crash survivors did in the end.
ultimately, his abilities were too much to handle, as evidenced by the others' parting words when they returned him to michael.