How would you measure our ability to use technology for good? I tend to think that humanity has collectively made some progress in this area, but it's more along the lines of
social engineering than moral progress. That is, we're not qualitatively more likely to do the morally right thing left to ourselves, but we have developed systems that reduce the consequences of our bad intentions. We turned down our first opportunity to drive ourselves into extinction, so for now we're at 100%.
It seems to me that "our" (humanity's) ability to use technology for good actually is keeping up with technology. Even if you count Chernobyl, nuclear power is less far less polluting on the global scale than the fossil fuel equivalents--and you'll note that nations around the world are working together to pay for the decommissioning of that plant, rather than allowing it to fester. Even the hydrogen bomb has sat unused for 50 years, something that hasn't happened with any other weapon in history.
The real danger comes if a small group of people can get access to extinction-level weaponry--say, a Stand-style superflu. That's the scary (and unpredictable) scenario. As long as a lot of people need to work together to immamentize the eschaton, we are relatively safe. But if a hundred people can wipe the rest of us out, we are probably going to be in big trouble.