Documentation should most certainly be updated as the code changes.
Programmers should realise that the documentation is just as important (if not more so) than the code itself. If people don't know how to use your wonderful API, then it's useless.
If your comments don't accurately reflect the current code, then either the comments are wrong, or your code is: it's dangerous to have outdated comments in the code - somebody may come along, read the comments, and 'correct' the code because the code didn't do what the comments described it as doing.
Programmers should realise that the documentation is just as important (if not more so) than the code itself. If people don't know how to use your wonderful API, then it's useless.
If your comments don't accurately reflect the current code, then either the comments are wrong, or your code is: it's dangerous to have outdated comments in the code - somebody may come along, read the comments, and 'correct' the code because the code didn't do what the comments described it as doing.