I'm from a small town in a small state - and EVERYONE had nicknames - many of us were the sons and daughters of the town's residents who also had nicknames. 

For example, I'm working one day - and a couple I recognize from high school (15 years after graduation) show up for dance classes because they're going to 'Cheesy's' wedding. 

Now - Cheesy got his nickname because he was a 7th grade fart monster.  Really.  It was awful.  Cheesy is now a grown man - and while I haven't detected the rate of his flatulence lately - I wouldn't refer to him that way now. But the couple I'm talking about really hadn't left home...although Cheesy had.

From my small perspective Kyle, it's overfamiliarity on a national level. Locally - I had two nicknames - Mule - given to me by my brother-in-law (who's 7 years my elder)- because he thought I was too much like Eeyore - and Packrat - because I have pretty good recall...

I've read that shy people use nicknames to initiate or force familiarity...