This would be a good one to add to the Ideas section--there are some similar, but not exact--I'm sure lots of people would vote it up. One of the reasons that the versions are not backwards compatible is that new features are often added to the new versions which are not included in previous versions.
My rule of thumb:
Never buy the first model year of a new vehicle, buy it in the second year.
In other words, getting the latest-n-greatest first is often going to have issues so getting the second generation is better as many bugs will have been addressed. When 8.1 came out I quickly threw it on our QA server for testing. Good thing I did as there were issues and 8.1.1 was born. QA is now upgraded with the patch and chugging along smoothly so now I feel more comfortable with upgrading production. I want my users to have the latest but not immediately.
I would recommend people set up a QA instance. It should be possible regardless of licensing (have QA and PROD servers) but check with your sales rep to make sure as I am NOT a Tableau licensing expert. Also, wait at least two weeks before pulling the trigger to upgrade to PROD.
Toby, that applies to "normal" customers. We are OEM. There is more at stake than our environments.
We will have customers using different versions of the server (8.0.3, 8.0.6, 8.1.1, etc). I may want to provide them new workbooks or updates - we have multiple customers using some out of the box workbooks we provide.
I cannot force them to absolutely have a specific version.
Plus, after trying it - if I don't use version-specific features (let's say whisker plot) I can just change the XML to reflect a specific version and it will open - so I believe it is possible.
I selected Tracy's answer as being the "correct" answer - it really is a feature request...
Link to idea: http://community.tableau.com/ideas/2902
Ah, I didn't know your situation fully.
Good Idea, I upvoted it.