The territory has been surveyed to some degree. For example, consider Wolfram's Elementary 1D Cellular Automata. Most are not even computationally universal.
On the other hand, David Eppstein - who has looked into the issue quite a bit - claims that gliders are "commonplace" - contradicting the spirit of Woflram's: "Except for a few simple variants on the Game of Life, no other definite class-4 two-dimensional cellular automata were found in a random sample of several thousand outer totalistic rules."
Eppstein's glider work is a bit of a caveat - but I generally approve of the idea that "life exists at the edge of chaos". Looking at Langton's "lambda" parameter, most automata are either off in the chaotic realm, or exhibit trivial, degenerate behaviour - with only a relatively small number in between.
First off, Wolfram's attempt to classify automata into four categories is flawed: it isn't obvious that every cellular automata falls into one of those categories and not all the categories are even rigorously defined. Also the claim that not many other "definite class-4" automata were found is unhelpful. The ways that things can turn out to be Turing complete are often surprising and non-obvious (cf for example the word problem or Hilbert's 10th problem.) So the claim that an automaton rule isn't obviously Turing complete is extremely weak evid...
I believe that life on Earth arose spontaneously. I also believe the galaxy around me is largely devoid of life. I reconcile these things using the anthropic principle.
I also believe that fundamental cosmological constants have values convenient for the development of life. I don't know if it makes sense to pretend that those constants could have had other values - it seems to me like arguing that e could have been 2.716. But it's certainly done. And again, the anthropic principle is sometimes invoked, as an alternative to, say, God.
Suppose somebody came up with a new theory of cosmological constants, that claimed that only certain values are allowable, and that a large percentage of the allowable sets would make life possible. Then you wouldn't have to use the anthropic principle. Wouldn't you be more comfortable with that?
But if that's so, doesn't it mean that you really attach a low prior to the anthropic principle? And that you don't truly accept the anthropic principle?
How do you do Bayesian belief revision when one of your alternative hypotheses uses the anthropic principle? Can you give a strong preference to the hypothesis that does not require it? Because I know that I would.