That's not wholly accurate of our reason.

Plainly, when we added our monkey patches, there wasn't really a strong bottling infrastructure. Most formulas weren't bottled, and many that were didn't often have the most recent version of the bottle available. Beyond that, pinning of packages to a specific version allows us to more closely track the versions utilized in production, and ensure folks are on a consistent version (as opposed to what was in the revision of homebrew they `brew install`ed them with).

We're certainly not opposed to a good checksumming solution that doesn't depend on the content of the formula file on disk.

Hope that clears things up.