I believe we need to be more respectful to human creators, especially now that it has become so easy to just “reimplement” someones work, to circumvent payment or license conditions or for whatever motivation. What would you do if this work didn’t exist? Well, I guess you’d have to do it yourself or use an alternative…
That being said, the Wolfram Engine is actually free for development and personal use[1]. I had a really nice experience with Wolframite[2] on Clojure as an interface layer and that works well enough for the few non-commercial things I do with it (evaluating WL expressions directly in the editor is such a nice experience!).
Of course, there are a few things I think we can do better than the Wolfram Language, but given all the available legacy code, there's really no point in making it slightly different and losing the ability to use that code. However, we might build an alternative syntax and frontend in the future that surfaces the capabilities of the Wolfram Language with a better UX.
I’m curious abut benchmarking. Wolfram claims they put a ton of effort into optimizing the speed of at least certain types of mathematical computations.
UX is an area I’d suggest working on. Wolfram was a real pioneer with the notebook style interface but nothing is meant to last forever. That might be an area to innovate without losing access to legacy codebases.
Maybe reimplementing something that already exists a couple times over leads to good things as well. I can imagine some subtle insights could be gained which matter to some of the user base.
The answer in my mind is fairly obvious: it's far more difficult and risky to do high-quality original work and give it away for free. If you want to see more original innovative work in open source, the two main ways to achieve that are to either do it yourself, or to pay others to do it.