Why didn't Rabbis Nathan Adler and Samson Raphael Hirsch not find it necessary to become reformers?

In the 1891 issue of the Year Book of the Central Conference of American Rabbis Dr Aaron Hahn, rabbi of Cleveland's Temple Anshe Chesed (from 1874-1892) asks a question that was surely on the mind of many American Reform rabbis of the day:





But, actually, this isn't the entire passage. The rest of it, which is his answer, is basically an ode to conviction: "Respect is due to every honest worker whether in the field of orthodoxy of reform. Let a man always be true to his conviction, be he a Sadducee or a Pharisee. Shame only upon the money-servers, the time-servers and man-servers."

This entire bit comes up in the context of these questions: ""...why do rabbis so often change their principle? Why have nearly all rabbis that come over from Europe so very orthodox, more or less changed?...Why do the rabbis not come out right at the start with the color and say this and that are our principles?"

All this is from a section called The Rabbi and Consistency; read it here. It is a unique artifact of the time.

Another quote, from Disseminating Darwinism: The Role of Place, Race, Religion, and Gender by Ronald L. Numbers and John Stenhouse:

In 1881, Rabbi Aaron Hahn joined the ranks of Reform opponents of evolution. Hahn...argued that if scientists proved evolution true, then "Jewish theology will bow its head before the majesty of truth and adopt it without further delay."....Nevertheless, Hahn firmly believed that the evolution of species was improbable, drawing support from [Isaac Mayer] Wise's The Cosmic God. He quoted passages from The Cosmic God that argued for a distinction in kind between animal and human minds and concluded that they "contain more common sense and more true philosophy than all the defenses of Darwinism together."