Looks good. Seems like you use it internally for your product as well. Our automated feed generator with inbuilt selector support: https://feedity.com might be of help to you. Have a look.

This is already built into the browser: in firefox, inspect element, then right click in the source and 'Copy Unique Selector' does this. In Chrome, you do the same inspect element, but the right click item is 'Copy CSS Path'

You're right. However, the purpose of this bookmarklet is to provide a streamlined method of getting the selector without having to go into the source. Using 'inspect element' is easy for me and you but for some people its enough to put them off trying to get the selector.