Its the incremental releases (Score 1)

I think a lot of the hesitancy to upgrade comes from when Oracle made the decision to go to the incremental release model for Java. For one thing, most shops that use Java use it for JEE; that's where Java made its biggest inroads for its popularity. These businesses will usually have a large portfolio of web applications that run on a JEE application server. For these businesses, the decision to upgrade Java versions also include a decision to upgrade version of JEE (now Jakarta) as well as a decision to move to a newer version of whatever application server they use. It generally means that they have to regression test EVERYTHING on the new version to make sure that everything still works. As you can see, this is a not a small decision! This is also not an effort that you want to undertake 4 times a year. While delivering more often sounds great in general, it was actually better for this kind of shop when Oracle (and Sun before them) did the large monolithic release. There is often some feature added in the new bigger release that might be compelling for that shop to undertake the upgrade despite the pain you know you're going to suffer. This often isn't the case in these incremental releases. Finally, you know that once you go through the upgrade pain that you won't have to again for at least several years. Therefore, its no surprise that businesses are choosing to remain on the last version of Java released under the old model.