>>46275116Because fire is cooler, seen as more destructive and powerful by kids with no imagination. It’s also an instantly recognizable element that enhances a Pokémon design. Charizard’s tail, Typhlosion’s mane, Blaziken’s wrist (although not immediately prevalent in it’s design), Infernape’s head/hair, Emboar’s colar and from Gen 6 to Gen 7, the fire is incorporated in tools (Delphox’s wand and Incineroar’s belt) and completely gone with in Gen 8 with Cinderace.
If previous Gens were made by nuGamefreak, Infernape would have a fire stick and Blaziken would have fire gloves.