Rob Williams complains that Eclipse plugins suck. Unfortunately he is right. Most plugins (and that includes some projects hosted at eclipse.org) don't come anywhere near the quality of the Eclipse SDK. Rob asks in a comment why the unwashed masses of plugin developers are allowed to shoot themselves (and the whole Eclipse install) in the foot. As usual, it seemed like a good idea at the time (an still may be).
One of the basic tenets of eclipse development is that there are no privileged clients. The idea at the time was to migrate all IBM dev tools onto a common platform. This would include web tools, c, cobol, you name it. It should be possible to write a state of the art tool for all these problem domains. At the same time, the platform should allow for all these tools to seamlessly integrate into the same workbench. It was felt that the platform would only end up with the appropriate degrees of freedom if the developers of the Eclipse SDK would themselves have to live by the same rules as all the "third party" plugin writers (a practice called "eating your own dogfood"). That meant that if the JDT or the update manager or whatever SDK plugin could plug in some functionality into the workbench, anybody else could do so, too. Voila a whole bunch of loaded guns conveniently pointed at your foot ;-)