As you said Google (and other search engine bots) are getting smarter, Google even acquired metaweb to understand natural language better and once the bots and the algorithms understand our language better, sentences with bad grammar will loose their meaning to these bots. A similar analogy would be w3c validation, it doesn't really harm but but if you have an h1 that you forgot to close a bot can easily think you are spamming the search results.
Correct grammar will be required in future
As you said Google (and other search engine bots) are getting smarter, Google even acquired metaweb to understand natural language better and once the bots and the algorithms understand our language better, sentences with bad grammar will loose their meaning to these bots. A similar analogy would be w3c validation, it doesn't really harm but but if you have an h1 that you forgot to close a bot can easily think you are spamming the search results.