Spotlight indexing of Time Capsule - feature or bug?

Question

I understand why backups are indexed: the ability to use Spotlight from within Time Machine is a fantastic feature.  But the method by which this index is created does not make sense where a Time Capsule is in use (or indeed most networked storage, but since many configurations are officially unsupported let's just keep this discussion focused on the officially approved one!).
Typically (from my sample size of 1), a complete system backup is of the order of 100GB; however, after the initial backup is complete, Time Machine only needs to copy modified files to the backup drive, which can lead to very small and fast subsequent backups: unchanged files are created in-situ with a hardlink to the existing copy on the backup drive.
A problem arises when, after a backup completes, Spotlight attempts to index the changes to the backup drive: it appears that it inspects every unindexed file (involves transfer to the local machine) including such unmodified/hardlinked files.  This therefore gives rise to a situation where a backup that writes only a few kilobytes to the backup drive results in Spotlight reading hundreds of gigabytes from that drive.
Even with a throughput of 100Mbps, this would take close to an hour and a half (in reality, especially over wireless networks, it takes many hours); meanwhile Time Machine reaches its next scheduled backup and cannot proceed until Spotlight has finished indexing.
Altogether, this appears to render Time Capsules useless for system backup (unless one is connected via gigabit ethernet, which is neither a requisite nor a desirable constraint).  One does not need to look far to see how many users this issue is affecting.
In previous versions of OS X, one could workaround this issue by disabling Spotlight indexing of the backup volume; however, since Lion (or Snow Leopard?), this is no longer possible.
To my mind, the design is flawed - some might call it a "bug": there should be a more efficient method of indexing drives, especially networked ones (ideally avoiding the redundancy of reindexing hardlinked files).  At worst, Time Machine could provide to Spotlight all the metadata it requires for the entire backup: thus avoiding the need for Spotlight to read such files from the backup volume.
...or have I misunderstood something?

Answer 1

nickety wrote:
I understand why backups are indexed: the ability to use Spotlight from within Time Machine is a fantastic feature.
That's not the reason; Time Machine requires the indexing in order to work, especially for the "Star Wars" display.
Altogether, this appears to render Time Capsules useless for system backup
That's not normal; you have something else wrong, possibly a corrupt index.  See the pink box in #D2 of Time Machine - Troubleshooting.
In previous versions of OS X, one could workaround this issue by disabling Spotlight indexing of the backup volume
Not really.  The backups were still indexed;  you just didn't get a message.  See the note in item 2 here: http://docs.info.apple.com/article.html?path=Mac/10.6/en/8991.html