As far as I am concerned (and I'll admit to being a StackExchange fan-boy), JSX is a superior site structure versus classic forums and mailing lists for many reasons. I find the comparison to be a "no-contest".
I have been and will continue to urge and support Joomla users that I meet via my local Meetup group and future conferences to become more active on JSX regardless of what they "have to offer". When more people get involved and they are shown the benefits of being a citizen of the site, everyone wins.
Joomla has too many communication channels for support and this spreads the talented problem solvers too thin. If there is a better platform than the Q&A here, I have yet to find it. Let's all endeavor to do more to make this site a better resource. Having this echoed from the Joomla leadership can only help.