>>37381260Because in Gen 1 it didn't get to benefit from its high Attack stat and its Special was decent at best. I don't remember it being quick either, but I could be wrong since its been a while. There was literally no reason to choose Flareon over Arcanine or Magmar.
To be fair though, visually Flareon was by far my favorite of the Eeveelutions until Leafeon made its debut. Jolteon looked like it was straight out of an 11-year-old's doodle book, its entire design just made to look as spiky as possible and Vaporeon looked like a dog-fish-cat-mermaid.