Pandoc is such an amazing piece of software. I used it to format my novel and made it part of a GitHub action to produce all the formats I required. I wasn't aware of templates, but some look really sleek.
I keep thinking that modern text editors are just flawed and markdown, with all its downsides and limitations, is what 99% is the people need.
You should be aware that pandoc markdown has extensive non-standard additions to the language to make it usable.
If you want a pure markup language that is simple, plain text readable and able to produce text more complex than what a type writer could manage in 1920 then restructured text is the way to go.
You may be overestimating technical abilities of 99% of the people. I tried to convert some to pandoc and failed miserably. Personally I love it, markdown is becoming more and more central to my workflows.
For the short, simple documents that most people make, a versioned, wysiwyg word processor is going to beat everything else.
I mean, they don't want to think about building the output, never mind controlling the process.
Haskell thriving in the wild!