Maybe, today, you just cannot? The proof is missing so far. No Java killer app that people heard about.
Yes, that's exactly the problem.
Not for us developers, but for the "sales & marketing guys" at the publisher houses, because they hardly got references to rely on...
You can do a "List of commercial games using Java" (see other thread, please) but the list isn't very long.
The only thing you can do is saying that you can develop THAT cheap and deliver such an cool game in THAT short amount of time. Then of cource, you need to be sure that Java really gives you the desired advantage in development time and budget. Are you?
But again: since I/we are new to the publisher they don't have got any reason to trust what we're saying; just what we're showing them.
So maybe it won't help much if the small studio says to the publisher: "trust me, I know what I do"...
(sounds like the cool Sledge Hammer btw. ;-)
Having secrets with business partners always is a bad idea....