You can't replace standard languages. Though there is some merit in trying to develop a basic dialect for teaching the language to freigners. Ogden did that for English (Basic English), and you can even access a version of wikipedia in basic English. In its simplest form Basic English makes do with less than 20 verbs.

Basic English - Simple English Wikipedia, the free encyclopedia

But I think that such a language can only ever be an entrance way to learning the proper language.