Kynn,
You appear confused by the meaning of the word "optional".
All the things I listed for packages are additional features you _may_ use,
not onces that are imposed on you so that they _must_ be used.
Lastly, I forgot to mention NAMESPACE support. Which gives pretty much
exactly what you outlined at the beginning of your post as a desiderata.
But it seems you know full well what you need, so by all means do charge full
speed ahead. But before I close allow me to reiterate that you are somewhat
ill-informed.
Packages do not impose anything. Asking to be included in a high-quality
repository such as CRAN does.
For local and personal packages you can be precisely as ad-hoc as you are in
sourced files. Yet you still have access to the very framework that gives
you _options_ for more structure.
Dirk