According to John Fultz
[...] if you want to influence WRI's priorities, the way to do so is to find other folks who have similar concerns and make yourself heard through the Support team. [...]
Which is not common knowledge.
So posting a topic tagged bugs and saying it was already reported actually decreases the chance of it being fixed or moving up in Wolfram's bug-fix priority queue.
I think this is so because someone, who is not aware that a serious bug isn't taken seriously by Wolfram Research unless they get several reports of it, won't report it after seeing that it is already known.
How can we overcome that effect while keeping Mathematica.SE's bugs repository clean and up to date?