I think any honorific has a distancing effect no matter what. And this would apply to Naruto too. But the way that he doesn't use them with anyone else's name. Well, he respects his senseis by calling them as such, but he never uses them with equals except in the case of Sakura. So there was a significant emotional attachment that provoked this use of a cutesy title for one person. That's the way I read it anyway, and that's what I think was intended.
The Sasky Kun and Nardo Kun kitten also indicates an emotional attachment, but it's obviously not as significant, since they are both polite characters (generally) and use honorifics.
We also have to remember that Sai brings this up when talking about reading books.
He mentions that Sakura not uses suffix's for Naruto's name means that she must be very close to him. I know this means pig squat now, but why would Kishimoto write that in the story if it wasn't supposed to mean anything?
I have to keep reminding people when writing a story or even a comic that all things done in it has a purpose. Whether or not that prupose changes, but at the time of creation there is a purpose. You don't just add stuff in and not have it mean anything significant. If a writer does then it si bad writing. Sometimes writers can be clever and use it for a misdirection, but that is usually for a ultimate purpose and not as an excuse. Sure, no writer is perfect and like I said some thing change, but that leads to question...
What was the point of Sai pointing out the Naruto and Sakura dynamic on several instances and making a deal of it all if it all meant totally nothing? This is why I still believe Kishimoto wanted to put NS and SK together because of how many hints he dropped in the story. It was SP and/or SJ who made him change it for the damn movie.