I think the major advantage here is that, whenever a person sends a patch which is not going to work on older kernels, he must also send a patch for compat.h/c.
Hi Antonio
This is where you are fighting again the kernel process. The kernel process does not care about older kernels, expect for patches flowing into stable as bug fixes. So anybody from outside of BATMAN will not supply such compat.[ch] changes.
Maybe its also time to evaluate the value of older kernels with newest BATMAN? Is the pain worth the gain?
Andrew