I agree with you in the fact that some, if not all, of Behe’s examples of ”irreducibly complex’ organisms have been found to be reducible. However, I don’t think his argument that ”irreducible complexity’ points to intelligent design as invalid, or that it is only a criticism of evolution. He specifically states that he was not among the first to criticize Darwinian theory with regard to the complexity of organisms, many other scientists have claimed the same and have done much research along these lines. Therefore, his claim is goes beyond “an attack on evolution”, suggesting that because organisms are found to be irreducibly complex, there is a good possibility that they were in some way designed.
Like you stated above, many of the organisms that he used as examples of irreducible complexity have since been found to be ”reducible.’ However, I do not think that invalidates his point”if there are other organisms to be found that are indeed irreducibly complex, how could this not be an argument for intelligent design?
If an organism was found to be truly ”irreducibly complex,’ I think the argument that it was designed is just as valid as the argument that chance and mutation put it together. It is important not to dismiss the idea of Design purely due to its stigma. It can be studied academically if given the chance.