What are Objective Business Reasons to Prefer SQL Server 2008R2 over 2012?
I don't know that you can really be objective about choosing a lesser version over a current version. It is more or less forced eventually. Hardware goes out of date and purchasing any new hardware may require using a more current version of Windows Operating System; which that in turn requires you to upgrade SQL Server. I actually had conference call over a client that is in this very boat now.

As well your hand can be forced by Microsoft's release plan. Once a major version is released you will reach a point that you can no longer purchase the older version. Which is the case now with SQL Server 2012, you can't purchase a SQL Server 2008 R2 license. You may use that version but you will have to purchase under the SQL Server 2012 licensing model. SQL Server 2014 CTP2 was just released the other day so after a certain number of days/months after the RTM release you will not be able to purchase SQL Server 2012.

The overall decision has to come from the business' money holders. Business meetings I have taken part in the one thing that is always considered when building a new system out for an application is licensing considerations (support maintenance annual cost, licensing upgrades, etc.). The pros and cons of licensing what version/edition should always be considered up front. I have been in environments where the business was feed the wrong information on what quantity/type of license to purchase, then when they were audited because of industry standards they got bitten pretty hard from it (or the scape goat got fired). It was ultimately their responsibility.

The best thing I would suggest is looking at Software Assurance. Especially since in the two years covered SQL Server 2014 should be released. You may pay a good bit more now, but with the discount pricing you will save a considerable amount of money when you go ahead and purchase SQL Server 2014 licenses. Especially if Microsoft decides to change their licensing model again, although I have heard nothing that indicates they are going to.