The market for 35mm film was and is still dominated by consumers, i.e. millions of snapshot photographers. Ektar 25 was one of the first victims of the super-hyper-zoom boom. Consumers bought camera models and lenses with huge focal range and poor speed. To compensate this, they started buying 200 and 400 ASA Films. So they don't think they need it - they actually require higher speeds.
The second point is, that one usually does not see any film differences on a 4x6" print.