I have two disagreements with the critique of SETI.
The first is the claim that superintelligences (SIs) would not want to talk to us because we don't want to talk to nemotodes. I argued previously in another context that this is a false analogy (I used the example of insects). We don't talk to insects because they can't talk. They don't talk to each other, either.
To make the analogy valid, we have to look at the modes of communications that lower animals use, and ask whether we interact with them at that level. This would correspond to SIs who talk to us at our level, even though they communicate amongst themselves in more sophisticated ways.
I suggest that we do interact with lower animals at the level that they interact with themselves. An insect has a simple model of the world, adequate to find food, avoid predators, mate and survive. We do interact with insects at this level. Insects are able to survive and even thrive around humans. We are part of the same physical universe and from the insects' point of view we are interacting and communicating with them just like other parts of the universe.
As our technologies improve and we learn more about insects, we will become even better at communicating with them in their own terms. We will learn to use chemical messengers and other methods to interact with them. This would be closely analogous to an SI speaking to us in our own terms.
Even though we are not capable of understanding all of what SIs say to each other, it is still plausible that they might choose to communicate with us at our level. Our own experiences with lower animals suggest that there are many motivations for higher animals to communicate with lower ones.
The second point is that it does not seem productive to imagine that the universe is heavily engineered by active SIs. Throughout history, we have succeeded by assuming the opposite, that there is no higher intelligence or higher power behind the observations that we make. In fact much of our scientific progress is due directly to discarding this notion that Thor makes the thunder and Apollo drags the sun across the sky and God created the animal species.
Why should we decide, now, that when there is a mystery in our observations, that intelligence is probably behind it? It's never been true before. We face a solar neutrino discrepancy now. Maybe SIs are engineering the sun? We have a missing mass problem. Maybe SIs are hiding mass? We don't have a good model for how life started. Maybe SIs brought life to earth?
Such "answers" are the end to inquiry. Sufficiently advanced technologies are magical and there is little we can say about them.
The weakest part of this theory is the assumption that although the universe is full of SIs they are not here in the solar system. It seems very implausible that they would have left our solar system untouched for all time. This means that we must reconsider the possibility of divine intervention throughout history. This is an historically unproductive tactic but it is the inescapable consequence of considering that we live in a universe fully populated with superintelligences.
I suggest reading Robin Hanson's article which takes at face value the absence of stellar engineering, and draws conclusions from it: http://hanson.berkeley.edu/greatfilter.html.