Antoine,
Allow me to explain my motivations a bit. Perhaps it will become clearer then. :-)
As a team, we have responsibilities. For example, that task that's on there right now is a problem caused by our actions; we pulled that extension for security reasons, then decided we couldn't reenable it due to design issues. Therefore our actions have caused a very real regression in our user experience. As the product manager, I find these regressions concerning, and we have a responsibility to fix them.
Right now, my only recourse to fix these user experience regressions is to ask politely for someone from the team to help me. I typically get a lukewarm response to these requests. Meanwhile, I get a fair amount of abuse directed at me by volunteers for not fixing these problems, because I am the public face of the team and it (outwardly) looks like we don't care to fix these relatively simple problems. Sure, it sucks for us to do these random tasks, but it sucks hard for our users too. We lose a lot of credibility with some of our volunteers for it.
So what I'm trying to do here is make it as easy as humanely possible for you guys, the overworked engineers, to pick these tasks up and get them done. At the same time, I don't want to get sucked into maintaining control over the task list, so
mediawiki.org was the simplest solution.
I hope that helps explain things a bit.