I hear they are upgrading, but it's taking longer because vBulletin.org has a lot of custom modifications and programming that needs to be migrated over to 3.7 before the upgrade can technically be run/fully complete.
There are several threads in the feedback forum about this topic, please see those.
As this is official discussion thread about new vbulletin 3.7.2 PL 2 I was asking here vbulletin.org is property of jelsoft, too. I am just curious why they did not adopt newest version.
This thread is to discuss the release, not the implementation on vB.org. For this we have the vBulletin.org Site Feedback, where this topic is already covered in a few threads.