First, its a pretty good DoT, even if you don't care about about the heal debuff
Second, if you wanna kill a healer, its pretty much required....and theres a ton of AMs out there roaming
Third, just because im solo, doesn't mean all my fights are 1v1. In fact, hardly any of them are. Its far more common to either be blob surfing, or to just start/join in small scale fights. In such circumstances, there's nearly always a healer involved, so the heal debuff is excellent.