I really don't like the idea of one language suitable for all problems. I actually like that there are different languages that are better suited to different domains.
In real life, you're right. It doesn't make sense to try and mash every language together just because. Its also potentially not possible anyway, since theres too many conflicting design decisions - though the ability to mold a language, through powerful abstractions and macros, like Lisp does, does indeed solve a lot of this.