Working on 3.1, I've decided to use only JQuery instead of YUI, in new components as well as upgraded ones.
One of my existing code is relying heavily on YUI's DataTable plugin, and as far as I looked, Moodle doesn't come with an equivalent plugin. While I don't disregard the possibility that I somehow missed a file or two, it seems that that the JQuery/AMD library is somewhat lacking in comparison to the library YUI offers. Although there are pleanty of third-party solutions for this specific case, what we need is a built in plugin in order to avoid ending up with other components, each using a different JQuery plugin the developer chose.