The problem here isn't individual researchers, but the field as a whole. Again, Gould outlines this in his book on the topic. Short version is, pretty much everyone knew that there were evolutionary implications for developmental biology, but no one wanted to say anything for fear that the everyone else would consider the research tainted by Haeckel's fraud. It took some pretty substantial names, and VERY good, well-documented, and thorough research, to convince everyone that this was a valid topic.