In my example below there seems to be a discrepancy / duplication in the required steps in OSGi resolution and Maven dependency support.
I have a jar which is dependent on a external 3rd party jar, in this case time4j.
Sorry but your expectations are not in sync with reality. First of all Maven dependencies are build-time dependencies. That's why you declare dependencies you know to be available in the runtime as provided
Neither OSGi nor Karaf can do anything about your build time dependencies. BUT with OSGi you can make sure your build dependencies are also available in your runtime and don't interfere with other libraries that might be available.
That's why you need to declare your imports and exports etc.
Karaf does help you with some of the dependencies for example with feature files. If you have a feature definition maven project, all of your compile scope dependencies can be included in one feature file.
BUT, the OSGi resolver only looks at the currently available bundles and nothing more, no connection what so ever to maven, if you want to have some sort of automagic resolving of external dependencies you need to make sure that you have
a) an OBR resolver enabled (this depends on the karaf version you are using, with 4.x it's already included) and
b) an OBR repository at hand, Karaf Cave would be the project to look for in that case, cause it can reside like a proxy on top of a maven repository.