“Why not show a picture of a woman who is dressed according to the rules? For example, when Rebbetzin Kanievsky a”h passed away, would it have been so terrible to put a picture of her in the paper? “
You have to draw the line somewhere. The editors drew theirs on the machmir side. It’s their prerogative. This “chumra” in policy makes it easier later on. I think that a picture of Rebbetzin Kanievsky would not have been terrible, but actually good. She was tsniut tzadekket and could inspire, much like pictures of Rabbanim. But once the policy was set it should be followed, tsniut tzadekket or not.
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“Because women don’t exist to be looked at. “
No one said that they exist to be looked at. We all have pictures of ourselves, family members, friends, Rabbiim, etc. Stam Reiah is mutar, Histaklut is assur. A picture which is meant to be looked at casually may become stared at intently. I will agree that one can easily lead to the other.