Your right, W3C is the industry standard, but this standard is defined by the W3C recommendations, not by a buggy validator. The aim is not to make not standard validators happy, it is to write code according to the W3C recommendations. Because the W3C validator is not able to check if code is valid like defined by the W3C I prefer other validators. If you don't like them don't use them, but you should accept what is written in the recommendations.
And it is not unnecessary code, e.g. the meta-tag is needed to tell the browser which script-language is used. You can not say: for most browsers it is JavaScript by default, so I don't need to write it. | 
