Randall Monroe Is A Wise Man

"When designing an interface, imagine that your program is all that stands between the user and hot, sweaty, tangled-bedsheets-fingertips-digging-into-the-back sex."

Yes, it's a little more than we'd actually want to think about our users, but replace the more graphic bit with "leaving work on-time", "playing with their children", or "having the information they need before the big meeting", and it does make a person realize an important fact. Unless you're making a game (and sometimes even if you are), your user could care less about your program. They want to interact with their data, or someone else's data, or data in the "cloud." Your program? They could take it or leave it, depending on the feature set, speed etc.

Your program will often actually be getting in the user's way.

Think about how much crap Microsoft took when they had Clippit, the annoying talking paperclip. Some people still make jokes about that goof, but when you think about it, it's a feature that kind of makes sense. An intelligent help section that assisted you with whatever task you were attempting to complete. Users don't like it when you meddle with them. They might be doing something horribly wrong, (or possibly just differently from how you'd do it) but don't meddle with them. They want to be left alone. If they want help, they'll find it.

That being said, I'm not trying to make a case against unobtrusive guides. If there is a somewhat confusing section of your program, it might make sense to include simple instructions on how to use it, or what type of input format is best, etc.

Remember, your users have better things to do. ;-P