"Super express" became kind of a misnomer as the project evolved over the years to become more useful.
The original iteration was one track with no stops. It was about as useful as the possibility of running QBL 3/1 in the peak direction; not very, because what goes in must come out.
Later it became two tracks and stopped at Woodside for the . This is no net stop reduction; the makes one stop between Queensbridge and Forest Hills and so would the super-express. At that point, the speed improvements would pretty much just come from rolling stock, but there's an additional wrinkle there as well; higher speeds lower your max TPH because it takes longer to come to a full stop. All the NTTs have 55MPH limits anyways so in practice we would've never taken advantage.
When you consider all of those things, the switch at 75th becomes an equivalent or bigger time saving than the new route.