I think people start to get weirded out when you start talking about changing the composition of the atmosphere that they breathe and also they don't realize how ironic that is. Aren't we already about 100ppm above pre-industrial CO2 levels already? At this point, why not throw some other gasses in there to try and cool it down a bit? Honestly, given that it's the cheap, half-assed solution, I assume it's the way things will eventually go.