Wouldn't this be better suited as a filesystem attribute set with something like 'mkfs.ext3 -O noperms' or 'tune2fs -O +noperms'? Then it's up the admin who created the filesystem to decide whether it uses traditional posix permissions or vfat style files are owned by whoever mounted it.
For instance, I may backup a filesystem to a removable drive, in which case I definitely don't want any automounter deciding to remap UIDs & GIDs at any point just because the drive happens to be removable, whether when performing the backup, or later when reading it because an important part of the backup (the ownership & permissions) could be corrupted.
On the other hand, I am tired of always telling people they need to 'sudo chown -R user.group some_dir' whenever they are copying something to/from my external hard drive and the permissions aren't liberal enough. A related use case is a machine used without root access that is still able to mount removable media (I'm specifically thinking of the machines in the IT labs at uni), where 'sudo chown/chmod' is not possible.