Is 80 columns exactly right? Probably not. From what I've read, the ideal is probably a bit shorter. In any case, having a standard that's in the right ballpark is a good thing. There will always be some complainers, but 80 columns seems pretty good for most people. It's nothing to do with punch cards, except that their design was probably influenced by the same ergonomic principles.
Applying a block indent doesn't increase the number of printed characters per line. And consider multi-column text as seen in newspapers--generally the principle is that it's the width of the text that matters, not where the column is located on the page.
Generally, the layout of characters within a block of text is directed to the task of reading within a passage. The layout of blocks on the page/screen is more about conveying larger structure and toward the task of seeking/navigating among passages.
I use 80 columns, personally, just because it's familiar, but I'd be just as happy with 100 or 112 or 120 or 160 or really anything as long as there's room to fit at least two editors on screen side by side.
Next up, let's deprecate the horrid mess that is the userspace terminal control subsystem on most modern Unix-likes: http://landley.net/notes.html#27-04-2015
(Keep in mind this is an orthogonal problem compared to the in-kernel VT subsystem, and I think it's Linux where CONFIG_VT is particularly bad.)
(also what the hell, why would you ever not use a fixed width font for coding)
