While publicity has fixed the nine old men in the publics' consciousness, I think that it's important to realize that the "nine old men" was something of an arbitrary title. That's not to cast aspersions on any of the nine, but the title was as much a result of studio politics as it was a testament to their abilities.
There were important animators at Disney before the nine rose to prominence. They include Ub Iwerks, Fred Moore, Ham Luske, Bill Tytla, Dick Lundy, Norm Ferguson, Dick Huemer, Grim Natwick and Art Babbitt. There were other excellent animators during the early feature years including Ken Muse, Don Towsley, Marvin Woodward, Don Lusk, Preston Blair, Bill Roberts, Berny Wolf and John Sibley.
There were several things that separated the nine from the rest, and not all of them had to do with art. All nine started their animation careers at Disney, so they had no other studio as a frame of reference; as a result they didn't question Walt Disney's artistic or managerial style. All of the nine stayed loyal during the strike and stayed with the company until their retirements. What Walt Disney had in the nine, besides fantastic animation chops, was confidence that they would execute his vision without arguing with him or abandoning the company.
While Disney no doubt valued their artistic ability, he himself was willing to break up the team. He moved Ward Kimball and Les Clark into directing for TV and he took Marc Davis away from animation for good after 101 Dalmatians to work on the theme park. By the time The Jungle Book was in production, only five of the nine were still animating. While the nine may have been running the animation department, their association was more managerial than artistic.
I am sorry about Ollie Johnston's death. He did great work and deserves to be remembered. I'm sorry about the eight who preceded him in death. Every animation artist who passes away diminishes the field to some degree by his or her absence. But I believe that artists needs to have their work judged and appreciated as individuals. Walt Disney's decision to tag nine artists with a nickname was as much a political and corporate decision as an artistic one, and as a result those animators who failed to fit into Disney's comfort zone for whatever reason have been cheated of attention they deserve.