As usual with arguments over translation, these are certainly defensible renderings. "Awe" does indeed get at one aspect of phobos, the sense of an encounter with vast force. But it misses the intense emotional content, the urge to flee.
We would be happier -- and we think the evangelist's point would be better served -- if the Lord asked, "Why are you acting like cowards," and the disciples, having witnessed a display of divine power, responded by "fearing a great fear," or, in colloquial English, being terrified.
They are terrified, it appears from a close reading of the text, less by the storm (which has already been stilled) than by the power they have seen manifested. They are terrified of Jesus.