I honestly had the sense that Morrison and Quesada had personal issues that made them embittered people, and they couldn't stand that Scott and Jean had a successful marriage.
With that said, I don't mind a well written Scott and Jean reuniting. At the same time, I don't want them to be back together just for nostalgia. If it makes a better story for Scott to be with Ms. Marvel aka Kamala Khan or for Jean to be with Miles Morales aka Spider Man or Quentin Quire I'd rather those stories happen. The o5 got a chance to do a complete doover, which rarely happens in comics and not in real life. So it would be interesting to see what different choices they make this time around, knowing how things turned out for their older counterparts.
The other thing both Jean and Scott know a lot more mutants their age, plus Scott is a Champion plus they met Nuhumans their age. With all these young superpowered people their age, who is to say that they would necessarily chose each other again?