Just because we can't magically address all causes of CO2 and pollution in general doesn't we should blindly ignore the issue.
Indeed. We should also, however, recognize that emissions reductions can never get us to net-negative CO2 and that is where we need to get. We should be investing heavily in research into carbon capture and sequestration, because it is the ultimate long-term solution to greenhouse gas emissions, the thing that will allow us to actually reverse global warming.
In the meantime, as you say, we should start by looking at the CO2 emissions sources that allow us to most quickly and cheaply reduce our emissions. The easiest area is electricity production... made even easier by the fact that wind and solar are the cheapest technologies we have for producing electricity, in many cases even when the cost of battery storage is included. And of course as we convert electricity production to non-emitting sources, we should electrify as much as we can the other areas where we burn fossil fuels.
But we also need to be investing in carbon recapture, because some things are going to be hard to convert and, as I pointed out, only recapture can get us to net-negative. We should also be researching geoengineering techniques, such as methods of reducing insolation. Geoengineering isn't a solution (e.g. reducing insolation does nothing to fix ocean acidification), but it may be a necessary short-term measure, and we should be prepared, having already done what we can to understand it in case we need it, and before we need it.
Carbon reduction is good, but it's insufficient and I worry that we're not putting enough into other approaches. A large part of the reason is that people are afraid that attention on anything other than carbon reduction will harm the emissions reduction efforts. That's not a ridiculous concern, but it demonstrates a lack of understanding of the scale and scope of the problem.