Why such a great tool exists in the first place? In the words of its founder, Mike Bostock:
Code is often the best tool we have because it is the most general tool we have; code has almost unlimited expressiveness. Alternatives to code, as well as higher-level programming interfaces and languages, do well in specific domains. But these alternatives must sacrifice generality to offer greater efficiency within their domain.
If you can’t constrain the domain, it’s unlikely you’ll find a viable replacement for code. There is no universal replacement, at least not while humans primarily think and communicate through language. And it’s hard to constrain the domain of science. Science is fundamental: to study the world, to extract meaning from empirical observations, to simulate systems, to communicate quantitative results.
Mike also offers some lessons learned from his 10 years of building open-source dataviz tools: 10 Years of Open-Source Visualization.