I'd say the main problem is human beings are not mature enough to be trusted with such a service, it will be a rape and pillage campaign for all your data and all your interests and all your imagination. We create predator services and pretend they are 'just services', burning the end-user's trust for any similar "services" after they sour from the treatment of the first one they tried. We have a serious maturity problem in the human species, and it is dragging all our progress down and backwards.