I thought so too but then I saw loads of chat on Twitter asking about the preferred setting so I wondered if I was missing something
The article and video I posted above are by Jeff Sauer - original GA beta tester and pretty much full-time GA consultant. He encourages everyone to go in to every property and set it to "do not expire."
You can always change your mind to a shorter timespan later if you need to on advice of your legal team, but once you've gone for 12 months and decide "oops, I would like to grab YOY data," you're hosed (at least insofar as you are using advanced segments and custom reports - your pageviews and sessions and bounce rate and all that from the standard aggregated reports will all be intact no matter what you choose).