I thought the same. Publishing small JS libs is easy, just drop a Bower file and register it. For maven I need to build it, sign it, get access to a central repo (can take days) and then finally upload it.

Of course, this means that the quality is often much higher, but I think the barrier is a bit too high as it is right now.

> For maven I need to build it, sign it, get access to a central repo (can take days) and then finally upload it.

Those are the steps required to host your artifacts on Maven Central. Hosting on other public Maven repositories requires less work, and if you host your own, you set the bar (you can even turn a GitHub repo into a Maven repo, and upload with a git push).

Having said that, if you've built something worth using, the extra steps required to publish to Maven Central are both negligible with respect to your overall effort, and are more than worth it (getting the initial access usually takes hours, or one day at most, and only has to be done once for the entire organization/author).

So far, the only projects I've seen that are not already hosted on Maven Central or any other public Maven repository (jcenter, Clojars, java.net and others), are usually short programming exercises or works-in-progress.