Wouldn't Mrs. Frisby and the Rats of NIMH make an excellent title for a rock band, with Mrs. Frisby as the lead singer and the rats backing her up on vocals and guitar? Can't you just see the band t-shirts and hear the roar of the crowd?
No? Okay, maybe it wouldn't make such a great name for a band, but it sure works for the book: we have Mrs. Frisby front and center and then the rats come in and do a lot of the supporting work. Who do you think deserves top billing in this ensemble? Mrs. Frisby or the rats?
When the movie version of Rats came out, the title was changed to "The Secrets of NIMH," because the filmmakers believed that people wouldn't want to go see a movie about rats. However, the movie was still about rats, so we're not quite sure how that logic worked. Which title do you like better?