>>58097230
The operative term is

>more

The point is that across the fanbase overall (including but not limited to /vp/) Iono is appreciated more, so Iono has something (or Nemona lacks something) that causes Iono to resonate more with people. And that something can't merely be apparent age, because then Poppy or Penny would be more broadly liked. It is more likely that the "something" is character design, personality, etc