Some dogs are sort of aloof, and others are lap dogs or real "cuddlers". What is it in their personality that makes them different? This is somewhat of a mystery.
What makes one dog standoffish and another dog extremely affectionate? It probably has a lot to do with their genetic make-up as well as their socialization skills. From an early age, your dog's breed and socialization skills (both pet-to-pet and pet-to-human) have an impact on his behavior.
This makes sense when you think about people - no two are alike. Some families and cultures are more "touchy-feely" than others. Some people like to cuddle and others don't.
The reason a dog likes to cuddle with you or with his toys probably has a lot to do with both bonding and comfort. Puppies cuddled with their mothers and littermates for warmth, and undoubtedly this gave them comfort. Dogs that are submissive are often more apt to cuddle and be near their gentle leader.