All dependencies are there to allow building the project AND launching tests, running or deploying to WTP (the scope is used to check which dependencies are deployed to the server and which are skipped).
Since you can launch your project from Eclipse, we need Runtime deps also in the classpath, although other options might exist.
If you feel this show work in a different way, please open an enhancement request suggesting this :-) . Patches are always welcome!
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Abel Muiño -
http://ramblingabout.wordpress.com/