It's not about creating a "useful" programming language, it's about exploring an idea by implementing it in a working compiler/interpreter and seeing it how wel

It's not about creating a "useful" programming language, it's about exploring an idea by implementing it in a working compiler/interpreter and seeing it how well it works in practice. Like other posters have said, the popular "useful" languages will learn from these small experimental languages and incorporate their features once they've proven how useful they are.