Haha. Reminded me of this:
http://youtu.be/9SxGnXkr9zk
I've thought that too. He's such an insanely annoying character it can't be an accident. Surely someone working on that movie realized...
I don't think Jar Jar is intentionally bad and I would imagine that a lot of people working on the movie knew how terrible it would be...
... but I get the feeling that George Lucas isn't a person that would entertain suggestions from staffers. I could be wrong, but c'mon, it's George Lucas.