The place this trips me up routinely is reading code on GitHub. I think they rightfully boxed the source file view to be fixed width so it doesn't blow out the rest of the layout. And it'd be inappropriate for them to wrap the code in that view. So, we have a scroll bar, which works fine, except on a trackpad on Lion.
Have you ever tried to read wrapped code? It's pretty terrible. Obviously that's opinion, but I've never come across anyone that's disagreed. Plus, your line heights now differ, which makes navigating vertically even harder.
I find 'smart wrapping' very easy to read. (Code is wrapped and auto-indented to the current indentation level.) I wish this feature was far more prevalent and it means that I don't have to worry about manually breaking the occasional long line, the entire line still fits within a window of any size, and the code remains perfectly readable.
I don't disagree that the usual implementation of wrapped code is pretty terrible (because it goes back to the start of the line, thus spectacularly breaking the indentation-based formatting - UltraEdit is the only implementation I've seen that gets it right), but it's still the right thing to do because the alternatives are even more terrible.
I didn't think horizontal scrolling was too bad, until Apple screwed that up. For a while, I could just use Firefox, but they implemented this same behavior, but without the nice animation. So, it's even more befuddling.
It's one of the many reasons post-Lion that I've decided to just move on to another OS. I shouldn't have to adapt the way I work to some OS updates quirks.
Actually, I prefer wrapping over scrolling. Sometimes my webbrowser may not be very wide, and having to scroll left and right to read every line gets annoying very quickly. This is similar to when people use code-view for quotes on HN, it makes reading a pain.
