Standard English is not yet complete, which is probably more true.
Well, we are changing the vocabulary a little, but not the concept. When I say a language isn't efficient or effective at expressing a point, you are saying it isn't complete. You seem to be seeing language as static, and I see it as plastic. (Being complete is subjective anyhow; who decides what is complete or not.) I doubt that any language is really complete, unless you're willing to defend that any culture is. But every language has the flexibility to communicate what the culture and people want to communicate. When the population see that their language is incomplete for what they want to communicate, they can "complete" the language very easily by changing or abbreviating patterns, making up words, or borrowing from other languages or within their own dialects. So standard English can't be seen as lacking, as if it were some permanent kind of helpless thing.
The Inuit may find English incomplete, or lacking, to express the different varieties of snow, but they can make up new words to express it, or even use their own Inuit words, and make English more complete. After all, English borrows words from all kinds of languages without chagrin for this purpose, probably more so than other languages. That probably makes English one of the most "complete" languages in the world — at least presently. Segments of the population pursue all kinds of different interests, which require an understanding of concepts that the general population doesn't have. And when they associate together to talk about these things forming new patterns and words, they help make the language complete. Jobs require special communication of key concepts that standard English just doesn't provide; and we call that jargon, since most people don't have a clue or don't care. And it fits in rather nice with standard English.
You are right that all languages can be used objectively and subjectively, which suggests they are more complete than you seem to be admitting. I meant tendencies though. Our Western culture has a long history of people intensely interested in the arts, literature, poetry, etc. (subjective) and sciences (objective) and all of this in many fields. It has had the effect of rendering the language very competent in a wide array of topics. Other cultures may have historically emphasized on the arts (like poetry), but maybe not so much on science. Their language may reflect the fact — but it doesn't mean the language is stuck there, or is permanently lacking. As the culture educates itself, and new-found scientists do research, become familiar with objectivity in the language, and communicate so on a daily basis, slowly the thinking and language begin to transform and take in these realities. (Perhaps Japan is a good example). The language becomes more "complete."
When you say that standard is lacking or incomplete, it seems like a dead-end, as if it were hopelessly innate; I would say that languages or dialects are neutral, or even full of potential — it is only as incomplete or lacking as the current population that speaks it.