The macro packages were a royal pain in the neck. As soon as you mastered one, somebody submitted a paper to a mill which demanded another. I alternated -ms and -me for ages because of this.

When we had a continuous paper wet process xerography printer, the cut-marks were a godsend. Once we stopped having that printer, they were a major annoyance.

For quite a long time TBL would spit out misformed tables. Mike Lesk told me this was an adustment added for the throwback function in the printer they used at bell labs and was needed to "shoogle" the table horizontals back into place for the next table. -Apparently printing a page-width worth of underscores in sequence caused an accumulating mis-alignment so they added some code to throw it back.