I don't mean to be mean to the original author -- I get what they're trying to do. It's meant to be helpful. But from my perspective, it just isn't.
Seeing an asterisk in front of a phrase that is simply not idiomatic in "English English" (note another phrase here I've always been a little weirded out by -- "English people") doesn't seem right. The * is used in linguistics to designate an ungrammatical sentence, or in language learning texts to designate an error. "Please eat more" is not an "error." In fact, it is not just not an error, it's something you could very well hear in a conversation between "English people."
It's not that I don't understand that some of these are uniquely Chinese phrases -- but for the asterisked ones especially, I just don't see any benefit in telling a student not to use them, other than helping them to become some imaginary version of an English Person.
In conclusion*, some corpus linguistics work might really come in handy in reshaping the way we think about this kind of stuff.
UPDATE: Shamefully I note no instances of "don't be polite" or "please eat more" in the British National Corpus. But the limits of what we have already observed does not preclude the existence of the reasonably plausible utterance, right? (Right?)
* PS: I usually use "in conclusion" ironically, to introduce something that is basically a non sequitur. FYI.