When you leave a job, you do the best you can to tie things in a nice bow for your employers, if it was a nice working relationship. But the reality is, you don't really owe them anything other than 2 week's notice and a little courtesy. Everything else is extra. It's certainly not a time to air out all the grievances that you were bottling up over the course of your employment, and that goes for both sides.
Sure, you might have a long list of ways you have felt slighted by your employer, and vice versa. We all imagine that moment when we read out an epic speech telling off our horrible boss, drop the mic and walk out forever. But the truth is, that stuff is probably best left to the movies. It's nice to have a good reference. But that's why we have Reddit, to live vicariously through other people's quitting stories.