One, because CFD isn't generally allowed at chargen in most groups, and tends to damage the host's abilities, as I recall. Two, CFD locks you into a single drone. Three, the character is the pilot of an anthroform drone that was used for... very personal protection. Four, this idea is more fun for me. Five, possible misidentification as a possessing spirit to those who aren't as astute, yet still manage to find out I'm not who I say I am.
Though I have considered how to do similar with CFD, it isn't really a chargen thing, and you don't exactly have control of it after chargen.