I think line limits are a good idea, though I sort of do them by feel usually. That said, 80 feels incredibly restrictive, a relic of bygone monitor sizes.
It's not just that, in fact the reason for limiting to 80 is mostly because short lines help readability because of how human eyes operate. Eyes prefer to stay within a small circular region located in the center of the visual field. Too much vertical or horizontal movement makes it harder to see, but vertical movement isn't an issue in text because of scroll, but horizontal movement is a problem.
This assumes that code should be read as prose. I posit that code should be skimmed, then the eye can track right if the code is relevant to the task at hand. This is all subjective, which is why I feel soft-wrapping is appropriate as it allows the coder to decide their preference.
Does anyone have rules that take into account indentation? I suppose too much indentation is its own issue, but seems like 80 could be flexible with your indentation.