a virus could kill 100% of its host, as long as it took a long time to do so while the host was still able to go around and infect others.

I don't think the 10% virulence is the reason (or the only reason) that SARS didn't make it to pandemic scale, I think it was everyone working against it and succeeding that time, which of course had the result of people thinking "hah, see it wasn't a problem, all those eggheads overreacting"

on edit: I think my main irritation is with the governments that did not put the proper preparation in the health systems (enough ICU preparation for example) for what was a foreseeable event.