In the context of this cartoon, the "bad" part is that the people who don't like YouTube's choice cannot just go somewhere else, because "we handed control of our social world to" YouTube already.
A business making a choice that some people disagree with isn't a big deal as long as there are plenty of alternatives for concerned parties to go to instead, but much like the .doc centralized control of document processing around MS Office, YouTube has centralized video content discovery around itself.
So there is Drew's point, that the YouTube ads are bad, and there is the cartoon's point, that we have given up and lost our chance to choose something else. Whether you agree with the first part doesn't change the second part, and that is (in my opinion) the bigger problem.
I also want to acknowledge that there are many different groups of people trying to offer up alternatives to YouTube, so yes alternatives do exist, but it is a very very uphill climb because of YouTube's dominance.