Because doing something like this is opinionated. The LaTeX developers try to do the opposite: they want to provide packages that cover as many usecases as possible.
And users of LaTeX are probably not knowledgeable enough or too busy to publish their opinionated subset of LaTeX as a class. I don't know for sure. There is no central body that has an interest in removing barriers, so you might as well ask me or yourself why I or you haven't published anything.
I developed something similar to this at my company, because we write lots of LaTeX documents and need shortcuts like this not only for brevity but also so that we achieve some consistency across the entire team. It's only for internal use though and thus not public.
