You could do two column layout that way too, because nobody should write more than 80 characters wide.

Why, so your friends using vintage vt100 terminals can read your code without scrolling?

No need to limit to 100 cols - VT100 with AVO (Advanced Video Option) or VT102 could do 132 columns!

Would have been cool to pair up a terminal like this with a BBC micro or other similar vintage computer for code editing, although the terminal would have been more expensive than the computer.

I find up to about 100 characters to be manageable from a readability perspective, but yes, not much more.