Kindle Renewal Ethics

I'm torn on this. Libraries are by nature a shared resource. As someone who has single-handedly paid for a library foundation in late fines, this is awfully convenient. Also, Manatee Library now supports Overdrive for kindles.
http://librarianbyday.net/2011/10/26/how-to-extend-the-due-date-of-your-library-ebook-on-the-kindle/

Just a friendly tip from your friendly online librarian.

It is pretty easy to “extend” the due date of the library ebook you check out to your kindle, just turn your wireless connection off until you’re done with it. This will allow you to keep reading the book until you’re done. The title won’t expire until you reactivate your wireless connection.

Can’t remember to turn your wireless off or just don’t want to keep it off all the time? Consider that handy email notice telling you that you have three days left that you get from Amazon (not your local library), you know the one that includes a link to buy it from Amazon, the signal to turn your wireless off if you aren’t done reading the book. When you’re done, turn your wireless connection back and on the book will “expire” as usual.

Is it important that there are not yet renewal options available for the kindle? What if the book hasn't been requested by anyone else? Your thoughts?