One huge issue is that many enterprise apps are only certified to run on older JREs. So updating the JRE will break the application and put you in "unsupported

One huge issue is that many enterprise apps are only certified to run on older JREs. So updating the JRE will break the application and put you in "unsupported mode" with the application vendor. So companies must stay at version 1.6.9 (or whatever).