Well, as a science-oriented person, this is the very trait which addicts me to beardies and fascinates me about them. They are -not- truly social animals with regard to their own kind, but they -are- unequivocally social when it comes to humans! Their behavior, when interpreted in the light of Occam's razor, must be interpreted as fond, if not necessarily 'loving' in a human or mammalian sense.
Basically, my personal hypothesis is that beardies have a partly developed social capacity which may be more developed in some individual dragons than in others -- which is why some of them get along better with other dragons than others do -- but it's that rudimentary social capacity which allows them to bond with us. They're intelligent enough to recognize that we are not predators, because we don't act the way they expect predators to act. I also think their capacity to distinguish different individual humans from each other helps a LOT. Not all animals can do that, and those which can't are the ones which don't seem to 'bond' with a human owner in my experience. Beardies can, though, and I think that is what allows them to become fond of us. Other animals may be able to recognize, generally, that humans bring food, and that their home near humans is a safe place. But a beardie can perceive and remember that this SPECIFIC human always brings food, gives me warm baths, keeps me safe, etc. As such, they recognize us as the source of many of their pleasures in life, and thereby become fond of us, in much the same way that humans become fond of things like cars and boats, because they bring us happiness.
In particular I think the cuddling reflects a sense of protection and safety. We are certainly large enough to drive off most any predator that a beardie would fear. So while our body warmth may be a small factor, I think it's more likely that they see us as a very safe place to hang out and go to sleep. They feel it is unlikely that they will be attacked by a predator while sleeping on our bodies -- and you have to admit, if that is what's going through their little heads when they do that, they're right!
Overall, while I do not think beardies are capable of "love" in a human sense, they unquestionably have their own set of emotions and feelings which are not all that different from ours. Less complex, their social potential being less realized, but fundamentally very similar.