Well, Ken, since you ask: I really don't like the idea of shooting people without their knowing in instances where they, the people themselves, become the primary subject. Often it can be as the butt of ridicule, of overweight (in a contemporary scenario especially) or even, as poor Diane A. used to do, of natural disasters of birth or circumstance.
I suspect that each of us already has a built-in moral compass that, followed, would prevent abuses of this sort, but it's possible that the marriage with photography lends such matters a taste of the hunt, and we all know how many animals died because of that glorious, deadly pastime.
Apart from the morality or otherwise, I simply don't have the cojones to confront people in the street in that manner; I know that I would hate to be so confronted... as far those bleats about 'then you should stay off the street', that's simply absurd and facile, nothing but an atempt at faux justification for selfishness and lack of common respect for others.
Having said which, I still enjoy seeing good 'street'. Especially do I like some of the work of William Klein: street fashion is cool - or was. Same genre but no victims.