Grammar is extremely important, and I am glad that English has many distinct grammar rules. In China, we signed a document that stated how about $90,000 would be spent. However, when the money was not spent correctly, it was pointed out that a sentence in the document was grammatically incorrect, and in fact it was ambiguous. Therefore, there was not way to take the matter to court, and we lost the $90,000.
Lose grammar and you lose the knowledge of singular or plural, definite or indefinite, male or female, past, present or future, sentence structures, descriptions, and so much more.
Image a road with drivers that had no rule. No speeding rules, no rules for if you get into an accident, no stop light rules, nothing. After all, the goal is to just get to your destination, isn't it?