1.7.2 is out on the Google CDN now.
Why? What would it fix?
We need a reason for upgrading any of our libraries/dependencies. If it fixes something, or allows us to do something better and/or faster, sure...but upgrading for the sake of upgrading isn't wise.
We're bug-free at the moment (AFAIK, related to jQuery), upgrading can only break something (and has, every time). It's not that breaks aren't worth it...if we get something from the upgrade then we deal with the breaks. If we're not getting something from the upgrade then it's just wasted time tracking down bugs...time we could be using to add more awesome to the site.