>the environment (or nature if you will), changed too drastically and quickly that most species couldn't adapt fast enough to survive.
These are not mutually exclusive. Mass starvation caused by environmental changes is a cruel kill off. I'm not sure what the point you're trying to make is.
Look at the holocene extinction event. It's been going on for over 10,000 years. It's only noticeable statistically, doesn't affect day-to-day life much if at all. Therefore it's not really cruel because for most species it's as benign as having a little too few babies to maintain the population.
And yes, I agree that human accelerated climate change is causing faster extensions. However, I could care less. When does the new MacBook Pro refresh come out?