I think the predominant safety issue is that there is a known failure in the steering mechanism. This failure manifests itself in loss of PS...but we don't really know the "etiology" of the problem causing the symptom, do we?
As for "could a Mazda Protege be safely operated w/o PS?", I think this is an example of how this board leans on the "safety" response too much. We don't know if the OP is a 250# longshoreman, a 88# beautician, or in-between. I think this would have a definite effect on what answer I'd give.
he design engineer, or the sales and marketing engineer thought it needed power steering, and so did you when you bought it. Why do you suppose that was?
Um, perhaps because "If we don't include PS, we can't sell this car to ~2/3 of our potential customers?" (Meaning most women, some men, physically disabled and elderly?) I could certainly see the sense in putting PS on a car that "I" preferred to drive without.