Currently, a seemingly arbitrary subset of features is enabled by default in our CMake configuration. Most users and developers building Blender want "make full", and I think that should be the default. This not being the case has caused a fair amount of confusion for people building Blender.
If there is a need for a configuration that is somewhere between "lite" and "full", that could be added. However my guess is that the defaults are mostly there for historical reasons. From before we had CMake code to dynamically detect if libraries are found, and before install_deps.sh to automate installing dependencies.