Why on earth would anyone like to make a language containing all languages? First it would be x^n times more work to put it all together, not only incorporating one language but many.
Second: Incompatibility. Most languages have different bases (structures) so they wouldn't work well together.
Third: All languages have their ups and downs, so the final product wouldn't be stronger than its weakest links. Since all languages have their downsides, the result would be one big slow weakling.
It would be easier to make a new language from the ground up containing all the nice stuff you want in it.
it's != its