Perhaps support for more VGA features can increase compatibility of DOS software on 32-bit hardware. 64-bit users won't be able to run most dos programs as there is no vm86 support when using a 64-bit kernel. In the end we need x86 emulation..
Dosemu (not dosbox) works nice here on my 64 bit linux distro. How are they doing that? Afaics dosemu uses vm86 instead of a full-blown CPU emulation.