The thyristor-triggering thresholds of the two rotors, a parameter influenced by the arc length of the sensor sector, may be in play.
Generation 1: I think the CDI capacitor discharges at a rate of 186,000 miles per second; doesn't need much rotor rotation to do its job.
Generation 2: Might have to wait a while to achieve total collapse of the electromagnetic field in the primary ignition coil windings, inducing a robust spark of the desired duration, before primary ignition coil winding saturation begins again . . . hence, wider sensor sector angle.
We may have discussed this issue before on this website: SOME CDI systems advance the spark, proportional to rpm, thusly: At higher rpm, the magnitude of the pulse from the pickup coil increases. The thyristor trigger threshold is reached earlier in the cycle at higher rpm; so . . . the spark plug fires sooner, proportional to rpm within design limits.
Make sense? Didn't think so!
Figures 10-14, 10-15; p. 203 of this reference address the ignition advance issue: