I think nowadays there is so much emphasis on leaving feedback (similar to leaving tips). Maybe it is not so in the US, but I'm feeling it in the UK. For instance, I went to my bank to ask two quick questions and then I was told that someone might call me to ask for feedback. Then I called my phone company just for two minutes, then I got the message that feedback is important. Come on! That's too much. For a two minutes transaction?!
I agree with comments above and the ideas mentioned are pretty good. However, may I say....you can't assume a buyer will leave you positive feedback. As a buyer, I wouldn't like to think that you expect me to leave you positive feedback. There are cases when a buyer feels ok, not great, with the purchase but wants to keep the product anyway. If you push for feedback he/she might go ahead and leave you feedback. But neutral! You can erase that with the 'kiss and make up' feature, but what if the customer doesn't want to change the feedback? You are stuck with it.