Gerard,
I don’t believe that the JSP spec specifies that java.util.* should be imported by all JSPs by default, but perhaps that’s not what you’re saying? However, to specifically answer your question, there’s no way to specify a default set of imports that should be used.
In the latest release of MyEclipse (3.8.2 for Eclipse 3.0.1) you’ll find a good bit more capability but I don’t know if it will resolve this issue to your satisfaction either. If you’d like to try it out, I’d suggest installing it in parallel to your current environment and using a copy of your current workspace.