Well, the monsters in Monster Hunter Stories often have different elements associated with them. Like some are fire - based, some ice - based. Their behaviors vary too. Some are more aggressive and will attack on sight, while others are more docile until provoked. They also play important roles in the game's ecosystem. For instance, a big monster might be at the top of the food chain in a certain area, and smaller monsters might be its prey.
Sure, monsters can evolve in Monster Hunter Stories. This evolution system makes the game more strategic and engaging as you have to plan and manage your monster companions' growth.
One reason could be to focus more on the characters and their interactions with the monsters. Smaller monsters might also make the battles more manageable and strategic. Another possibility is to give the game a distinct visual style compared to other Monster Hunter titles.