What makes it simplistic for me is really the idea that we can make the climate better by tinkering with a single variable (temperature in this case) - I'm not convinced we even know what 'better' is, let alone have enough understanding to predict what the side effects would be. What if we cause some imbalance that doesn't immediately manifest any problems but has a detrimental longer term effect?
I do take your point about space mirrors and the ability to experiment, though - certainly more appealing than man-made plankton blooms shudder - and I think you hit the nail on the head with respect to the political issues!
Temperature as a single variable doesn't deal with /known/ problems.
Besides the well-known effect on temperature, CO2 also causes ocean acidification, which among other things kills coral. In its own way, ocean acidification is far scarier than global warming, because there is absolutely no question that it is taking place. While you need a PhD to analyze climate data, you only need high school chemistry to demonstrate ocean acidification. Moreover, you have to deal with the carbon dioxide directly to solve this problem; you can't just try changing the albedo of the Earth, through mirrors or surface reflectors or particulates in the upper atmosphere. And worse: simply stopping where we are may not an option. The current levels may already be long-term undesirable.
Honestly, by analyzing fossil records of CO2 in past times, like the Jurassic period, I believe that somewhere in the ocean there are creatures with genomes adapted or rapidly adaptable to an increased acidic ocean.
The geological average of CO2 in the atmosphere seems to be about 20 times the current amount.
Not necessarily corals are the optimum staple life form of the oceans.
I do not claim to know anything about what would the optimum staple life form in the ocean, I'm simply open to the possibility that an increase in CO2 could lead to a improvement in photosynthesis ability for algae and therefore an increase in ocean life.
They were; I just picked that as a convenient example of a non-reversible idea. Once you dump the iron in, you're committed. It turns out that in a dynamic system (ahem) that just smashing one of the inputs doesn't guarantee a linear response, but regardless, you're committed once you've done it.
(It turns out that in this case the system tends towards stability. There are good reasons to believe that most changes we can make will also be neutralized. But there's no a priori reason that the same experiment couldn't have experienced a wildly disproportionally large response instead.)
Ah, but with space mirrors we don't get "temperature", we get temperature in locations. You don't just point the mirrors "at Earth", you point them "at Utah" or, well, engineering-wise there's nothing really stopping us from getting it down to a few hundred square meters or even tighter, which is why this can be such a weapon. But it's also why they really are the best solution, they have fine-grained control over many things and can even be used to do things like significantly increase evaporation in oceans or something, not just control temperature directly.
I do take your point about space mirrors and the ability to experiment, though - certainly more appealing than man-made plankton blooms shudder - and I think you hit the nail on the head with respect to the political issues!