Marvel’s Defenders

I quite enjoy Marvel’s movies & TV series – all the ones based around Avengers and related characters, as well as Daredevil and Jessica Jones.

But I refuse to get my head around why are they called Avengers? If they have the power, and the freedom, to act and intervene as they please, why do the superheroes wait for bad things to happen before they can avenge them?

Why not act proactively to prevent and defend? I’m starting a petition to name them Marvel’s Defenders. We want prevention, not just cure!