"Plant life benefits from an increase in atmospheric CO2, does it not? Increased plant life benefits other living creatures, does it not?"
Answer is of course "Yes".
But at the same time that we are increasing atmospheric CO2, we are decimating rain forests, and paving vegetated areas, and desertification is rampant in many areas - thereby completely undermining Earth's ability to naturally equilibrate.
FWIW: I am not a climate change scare monger - I am more of a human overpopulation scare monger since that is the root of *all* environmental problems.