You make a very interesting point. To some extent I agree with you: color, colour and kolor are for example basically interchangeable.
However, I do think there is a case for some kind of standardisation. In the middle ages there was none, but standardised rules for writing evolved so people could understand what the other had written and people could be taught and learn the language.
I am not against updating spelling rules of my own language (Dutch) or English to be more in sync with the current phonetic pronunciation. (knowledge -> nollidj) I even willing to concede that grammar evolves. But people should write sentences that make at least grammatical sense: "They're in the house" instead of "Their in the house". Otherwise the people intended to real the text will have trouble interpreting what is meant.
I like what the Scnadinavian languages have done in this regard.
My point is: There needs to be a standard, or it will quickly even become impossible to discern in what language a text was written, let alone what it means, for someone not familiar with the writer.