Projects that announce by a legendary member is not always a promising projects. But, sometimes a promising projects is conducted by a legendary member because this rank is high. I personally will research project first beside announced by legendary member.
you are right. besides that, the most important thing is not whether he is legendary or not, but whether the project he is carrying out is worth it or not. Well, looking at BM is only a few percent of the research that needs to be done. besides that, BM is not a determinant of the success of a project.