I'll add this because I think it's worth mentioning. It's not just the lack of gratitude. That doesn't bug me. I ignore manuals all the time and don't think twice about the guys who wrote the ones I read. What bugs me is the outright hostility that people seem to respond with these days. Use the "wrong" (even when technically correct) word and people will go ham on your customer service people. Use too many words to describe a "simple" operation and they'll lose their crap too. Give a torque value and they'll expect you to include the damn torque wrench (and will always mix in pounds and ft pounds, every damn time).
People are soft and sensitive these days and they feel no need to hold back against "corporations" because rarely does a company fight back against a customer - we do share stupid emails and laugh at them though. A lot.
When we start spending more time "helping" customers through their inability to read than we do fixing real issues, the instructions become a hinderance. If anyone thinks it's possible to write stuff to be universally understood - it's not. That's why we get pictogram these days too. Yay for the lowest common denominator, right?
Its easier to answer a customer's detailed question than it is to write 47 pages of legally-approved and non binding direction with 283 warnings not to gouge your eye out with a screwdriver or use the provided tool for self pleasure....
Usually if the same detailed question happens enough, manuals get updated. But in my experience, every customer is different and so the questions vary a lot too and conditional directions (if this, then that, else do this..) are impossible for 75% of people to follow - no joke.