I think that an important use case for such a patch is being completely overlooked. I basically just wrote the same patch and we are considering deploying this patch internally on some of our servers. Such a patch can be very useful from a sysadmin standpoint to prevent many permission related mistakes.
Picture a data serving daemon which runs as a non root user and which needs read/write access to an entire volume of data. It is not uncommon to place this data on a single partition for ease of management. All the files and directories on this partition need the same simple access policy and would be greatly served by the simple uid and gid options suggested in this article. Any other ownership of any data on this partition is inherently an admin mistake and serves no other purpose than to be POSIX compliant. Without such a mount option, it is only a matter of time until a mistake bites the service (an admin mistakingly copies a file as root, the service can not write to this new file...).
How many admins have cron jobs which scan an entire directory tree to verify that every object is porperly owned to combat (poorly) exactly this? Such cron hacks should be easily eliminated entirely with this patch, please apply it right away! :) Backport it even to every kernel in every distro still used in production!