See http://bugs.archlinux.org/task/6465 for the original ideas that inspired this.

Typically packages assume anything listed in 'base' in our PKGBUILD tree is installed on a system, so these packages are never listed in depends or makedepends arrays in other PKGBUILDs. If they were, it could quickly get out of hand, increase the chance of circular dependencies, and other possibly unwanted things.

On another note, pacman could unwillingly remove one of these packages if only a select few packages list them. This would occur when a package is removed with an -Rcs operation, and tracing the dependency chain caused a base-level package to be removed. phrakture and I have some ideas for preventing this- add a third option under install reason labeling the package as essential.

In the other bug mentioned above, the idea of a 'base' metapackage was mentioned. A 'base' group may be a better idea, containing only the bare essentials, and perhaps leaving out some of the other things currently in the base/ directory- mdadm, etc.

Basically, this bug is open for some comments and thoughts from everyone on some more logical system that guarantees certain packages on users machines so they do not need to be mentioned in PKGBUILDs.