The reason is given in the second sentence of the readme.
> This is designed to be a language to teach compiler development with.
That is, this is the language a student would implement a compiler for. It's in line with what you'll find for most undergraduate compiler courses in terms of complexity.
Why not? Lots of language designers create or work on more...
Matz has Streem, SPJ is working on Epic's new language, the creator of Pony is working on MS' project Verona, probably lots of others. Doubt it will supplant Odin though, considering Odin's being used professionally.
