It's called for. The last set of cottered cranks I worked on had each of the problems I listed ('73 Raleigh 3-speed) and was therefore not an exaggeration. You could have avoided filing the pins, but then your cranks would have been like 170 degrees apart. If you grabbed both crank arms you could probably feel the play as well. Then, riding them 5 miles would create either play or would move the position of the crank again.

They suck -- period. They're never worth messing with, and any potential bike that has them should immediately have them removed as a first priority. Other than learning to drive the pins out and remove the cups before trashing the entire unit, I don't even see the value in a mechanic learning to "work on them" -- (which basically means bashing on things with a hammer, maybe using a punch, and using a metal file to do a cheesy job of filing straight.

It's like trying to learn to hit knuckle balls in baseball -- you could learn it, but you might ruin your swing for life. Why bother with it?