I don't understand what you mean by "ruby needs RubyGems and Bundler to compete with maven."
Sure, and Java needs maven to compete with RubyGems and Bundler.
?
Oh wait, you think it's significant that on ruby it's two cooperative tools with two different names, compared to one tool on Java? I don't see how that matters too much in practice. (But it does, in real life, is it really just maven, or is it maven, and definitely ant, and maybe ivy too? heheh.)
I will admit that I find bundler a lot easier to use than maven, but I'm definitely a rubyist more than a javaite. I _think_ that someone who only occasionally needs to use ruby will find bundler easier than someone who only occasionally needs to use java will find maven. But maybe that's just my own prejudice, I could be wrong there.