I think the term was marketing but the move (away from straights and toward "safetys") was mainly societal: because it was the latest, greatest thing. It was seen as more high tech etc. A modern parallel was when people threw away (I know people who literally threw them away) their vinyl records when CDs came out. The buzz was that they "sound better," which they absolutely do NOT but that wasn't the reason so many people jumped ship. It was to be on the tech band wagon.
Edit: BTW I have all the old vinyl I bought as a kid, some from my parents and even some 78s from as far back as the 1890s. I have straight razors that are newer.