Buildtool is a set of perl-scripts/packages to build lrp/leaf-packages from source. Everything in the build process is automated, from downloading the sources and applying patches to configuring/building the source and creating the lrp-package.

Granted, the initial setup of a new package takes some time and tweaking, much more so than simply doing the compile manually would. So, for a one time shot, a package that will never be updated or modified, integrating it into buildtool is probably not worth the hassle.

But if you have a package that's security related (and therefore likely to receive security updates regularly) or one that is still under heavy development and new revisions are released all the time, the time invested in buildtool will pay off very quickly - since usually, all that's needed to integrate a new version of the software are a couple of changes in the config-files.

Besides, creating lrp-packages by hand can be tedious and error prone. And if the developer has to spend less time assembling the package, he can use that time for testing the package (or creating new packages).