I'm basically on the same boat as Aegis on this. Unless I had wanted them forever, or had them and grown attatched to them over time more than normal (with the exception of starters; which I never will/have nicknamed them) I wouldn't give them a nickname. Apart from that, I think nicknames, though a great feature to the game, are a waste of time. Because no matter what, a Charmander named Krissella or something is still going to be a Charmander and it's not like that really effects anything in the game. Unless there is something I'm missing. Apart from that, I hate thinking when I don't have to. So why would I spend hours trying to think of a nickname for something when I know eventually it will just end up evolving and then I'll have to think of a new nickname.
That used to happen back in the days of Red and whatnot. Once they evolved, I didn't think that the nickname really matched it and didn't know much about the Pokemon in the game back then, so I wouldn't have anything to relate to.