toilet paper - over or under?

So, today, as I was changing the toilet roll, and carefully making sure that the toilet paper was over, not under, I found myself wondering why I care.

This is an issue of great debate among many people. 

Why do we care?

Does it effect the way the toilet paper functions?

Does it change how easy or difficult it is to extract it from the roll?

Seriously, why the fuck do we care?!?!?!?!