I think the comparative biology approach worked out very well, because nothing was known. When other systems were so difficult to study, microbes were the obvious choice and they served as wonderful models. And now, we know so much about those aspects. It is time to look at the unique nature of microbes. That brings us to the next question.
Bacteria are so surprising because of their metabolic diversity.
It is not surprising that the ability of bacteria to conjugate with plants could not be foreseen. When I was studying Bacillus subtilis many years ago, we could achieve DNA-mediated transformation only if we used the same strain as donor and recipient. In fact, that was one reason that some people suggested it was foolish to consider the possibility that DNA could be transferred from a bacterium to a plant. You did a post-doc with Joshua Lederberg. At that time, bacterial genetics was in a much more primitive state of understanding, and surely there have been major advances since that time.