Have you ever noticed that kids don't really have socially-recognized "personal space"? We seem to acquire it as we get older, but we certainly aren't born with it. If you know the parents of a baby, for instance, it seems generally accepted that you can touch the baby as much as you want -- you can pull his hands and feet, tickle him, poke him, even pick him up, and he has no say in the matter. He may start crying, but often the parent will then try to soothe him so that you can touch him again. If you think about it, it's quite odd.
As kids get older, more verbal, and more self-aware, they eventually start telling adults and their peers to leave them alone, to quit touching them, talking to them, looking at them, &c. Anyone with kids or siblings has seen or experienced the "tell him to get his finger off my side of the seat!" argument and the ever-popular "tell him to stop looking at me!"
Even still, kids as old as 7 or 8 want to be picked up, tossed in the air, and flown around the room. Maybe adults would too, except we're too big. That's the stage when "personal space" really becomes entrenched: the child is old enough to want control over who invades their space and when, but they still want to be picked up and played with -- only eventually they're too big. Maybe they see it as some sort of rejection, or maybe it's just the parents saying "you're too big [old?] for that now".
But it would be pretty cool if there were giants to carry me around and throw me up in the air.