Cyno i would bet it is TRUST ... he hasn't learned he actually can trust you yet to get that close, some of his aggression might be fear.
Cuddling ... never had many dogs that truly liked cuddling holding and such ... but my current boy(american bulldog) is an absolute lovey dovey and not only does but seeks it out
i hear that dogs dont like hugs most of the time because they naturally see it as a threat, i think its all about trust levels.
As for cuddling on the perspective of someone whos interests are exclusively cats and lizards, they usually love the attention and warmth if they do trust you.
My dog used to be like that, now he is quite into physical contact. It only took some time. Couple of years actually. He still does not sleep under the blanket with me (but that is probably because he is hot, literally and visually :P). I remember being sad about him not being into petting. But you just need to keep building the relationship and it will come over time.
Great Danes love to cuddle. It's just damn awkward to watch TV with one sitting on your lap.
My girl used to love to cuddle all the time. Now she like laying at my feet.
Mine may cuddle sometimes. But usually it's not for long. My roommates dogs love to cuddle though.
Both of mine are long hair coated breeds. After fifteen minutes cuddling they get too hot6 and get up and lie by my feet.
