For The Unrush, the sleepy coffee cup helps give the brand that calm, relaxed feeling. For Le'Patty, the burger character is playful, but still looks sharp and clean. Koality's koala has a relaxing look holding a cup of coffee.
Every brand is different, so I don't think every mascot needs to have a lot of poses or expressions. Sometimes one character in one pose can do the job, while other brands need more variations to work across different places.