I hadn't looked at:

http://openjdk.java.net/jeps/201

before - nor on the linked jep 220.

I wasn't really aware project jigsaw and jdk 9/10 had quite so ambitious goals (paraphrasing:... Getting rid of the old and inefficient jar format based on zip file format...).

While technically correct the maven-jlink-plugin is in alpha and I’ve not yet seen any application packaged this way. If you’re aware of any open-source project doing this I would be very interested :)

For large projects, fat JARs are slow to build. Unless you bundle JARs inside the JAR and use a special classloader, like Spring Boot... I don't use them at all because it's a pain. Plus you'd probably want to put your app code that changes in a different layer if you're doing docker images, as opposed to the other 90% of your app which is dependencies that rarely change