Owner of Jbuilder was Borland. Jbuilder was a fast and nice IDE. As far as i see, later, Borland decided to reduce the development cost of Jbuilder for them and they transformed it to an Eclipse based IDE. I did not follow the news or use it after these events but i guess this is the reason of reduced interest for JBuilder.
And you can discuss Jbuilder related things on
Other IDEs forum. And once enough people discuss Jbuilder related issues there, we are ready to open a separate forum for it..