The desire to suppress "flamewars" is great, but once one has a tool called a "flamewar detector" it's easy to lose sight of the fact that not everything that triggers the detector is in fact a flamewar that should be suppressed. Occasionally (rarely? frequently?) what's being suppressed is high quality fast-paced discussion. Once one has a tool that provides some degree of the benefit (the flamewar detector), I'd guess that it can be easy to confuse the actual goal with the incidental behavior.
I'm intrigued by this idea of "expected failure". That is, cases where the outcome is actually non-desirable, but since the software worked according to spec, the failure is considered a success by those who designed the software. How do you go about assessing whether the suppression is having the desired effect? Is it based on something more subtle than slowing down the rate of commenting when it's going "too fast"? Are there knobs that can be tweaked to keep it from triggering on desired discussion?