I have to admit my memory of the Soong episodes is kind of vague ATM, but was it ever established if Soong was that well known? I always thought that perhaps nobody outside of the people that knew him personally were aware of him and his work with AIs. Or at least he wasn't well enough known that people would immediately recognize his likeness.
Yeah, but people knowledgeable in the AI field would've known of him or known him personally, and those same people would surely have studied Data once he was discovered. Besides, as I recall "Datalore," the away team recognized the name "Noonien Soong" the moment they heard it, so he can't have been that obscure.
(The problem, of course, is that the producers originally had no intention of having Spiner play Soong. I mean, his name is Chinese in origin. They had cast Keye Luke to play the role in "Brothers," but he died soon thereafter and they had to recast. So when they decided to have it be Spiner in makeup, it created a retroactive continuity problem.)