When I hit the backspace key, there is a significant probability that I will have to wait for the old page to download and render again. (Wether the re-download and re-render happens seems to depend on how the maintainer of the web page set the cache-control.) Although I understand the advantage to non-technical users of doing things this way, as a technically-adept user, I would have preferred for the back button never to cause a re-download or a re-render. (I know that I would have no trouble figuring out when manually to cause a re-download (using e.g. the reload button) because that is the way Lynx did it years ago.)
My point is that the main reason I open new tabs is so that I can definitely return to the current page without waiting for the page to re-download and re-render. I would be happy with the back and forward buttons and the history menu if using these things did not often cause me to wait.