>>36291083Because it was the most plausible choice to do.
Japan is into tigers: ckeck!
Japan is into wrestling: check!
Japan is into anthro-animals: check!
If you combine all three concepts you will get Incineroar. We Westeners might not understand, because we are fond of authentic, real-animal-looking creatures which look more feral or pet-like, however it is not uncommon in Japan to combine animals witch characteristics of a human.
Just because you don't like this design does not mean GF chose this design causelessly.