I see you don't quite approach this from a business angle but merely comment as an individual. I say this because I do represent a (small) business and well... Your arguments are flawed, even though I actually agree with some of them. The problem however is the combination of them:
#1 Security - lower vulnerability counts, with fewer days at risk and fewer critical vulnerabilties that are on average fixed faster than any competing OS. Full support for secure boot.
However, when working with a server version which is still being supported and maintained, how would this be an argument for upgrading? Its like saying that the current servers are no good when it comes to security, and when looking at Server 2008 I really beg to differ. And its not as if patches for Server 2012 will be released any faster than 2008 or say 2003.
#2 TCO - lower cost of support / ownership in an enterprise compared to competing OSs for the vast majority of uses.
This I could actually agree with, to a certain extend. However, it has a small flaw in its reasoning; for the best performance you're better of not merely grabbing a Server 2012 version; you'd also be looking at a client OS upgrade. Not saying that Server 2012 can't cope with older clients like XP, Win 7 and so, but its not optimal.
And upgrading a whole park really puts dents in your TCO picture. Another very important TCO aspect is durability and reliability; you can't claim that Server 2012 has proven itself on these parts; it didn't. Couldn't have because its quite new.
Server 2003 and 2008 otoh. are server environments which have been out in the open for quite a while and really earned their marks (IMO). I can easily argue that $company could be better off upgrading from 2003 to 2008 because I have a very good idea what both can and cannot do. But with 2012 all you can do is follow doctrine; and that's not good enough.
#3 Functionality - The market leader in many respects.
"Results obtained in the past are no guarantee for the future.".
#4 Performance - Significantly outperforms other platforms in common uses - e.,g. worlds fastest fileserver.
Yet if you're not so much into the whole virtualization then the performance aspect can easily start to work against you, considering how this server version is fully aimed at supporting virtual instances.
Best tool for the job applies here, and although 2012 is a good product its simply not better than the previous versions by definition. I can come up with plenty of scenario's where a 2008 or maybe even 2003 server would be much better suited.