The people who write and deploy software to limited markets appreciate it. Have you seen how many Windows 2000 deployments are still out there? It's the same with BSD and Linux - there are a lot of 10+ year old systems out there doing useful work. Functional binaries save hundreds of hours of work to maintain the software.
I don't think your argument applies: you are talking about running new binaries on an old OS/kernel, but this is not guaranteed to work. New system calls and kernel interfaces are added all the time, so new binaries are unlikely to work on old kernels. The promise is in the other direction; old binaries are guaranteed to work on new kernels.
At my office, we actually still have some Windows 3.1 servers in production alongside some Windows 2000. Replacing the software running on it has proven to be a bit more of a trick than previously thought.
