"Today is the 5th of December, 2017."
Hm... I don't actually have objection. It depends on the context, and when we make a statement, it should not be omitted, whereas if it is a verbal reply to a question (What date is today?) or if it is a clause, it's perfectly alright to omit. Afterall there are some limitations for using a 主謂句 (no verb).
IDK if this is normal, but in the little boxes with characters, I had no way to make the phrase. It was good in the end, as it forced me to switch to keyboard input and type without crutches or training wheels. But there's no point in having it if it doesn't work, right? Kind of a false promise. Next time I'll take a screencap.