I'll agree that there are traditional grammatical conventions that we can let go. Split infinitives and sentence-ending prepositions? These are impossibilities in Latin, and applying them as rules of good grammar to English (a Germanic language), is unnecessarily pedantic. "However" as a post-positive conjunction? I can only use it that way myself, but I'd never correct anyone else; it just doesn't matter to 99% of the English-speaking population.
In my opinion, however, spelling should still be considered important.