Why is this a good thing to do ?

Emmm, Well, maybe for gaining some confidence or maybe just for being happy sounding more naturally?

For me, I love it when I throw out some idioms or the most colloquial expressions, then have the native speakers wide opened their eyes, "impressed" by "my natural language"! And I'll explain :"no, no ... actually, It's just the third phrase i learnt right after 'hello' and 'nice to meet you'. " We'll actually laugh out of it. It's fun : )

I agree. Pretenders and exhibitionists could suffer a lot themselives at some point.

It's about how one sees himselfe. A man who is polite and talks straight could be just condescending and ignors other's feelings, while rebellions don’t necessary come from riots. The action is just the surface, it reflects the personality, but only in a sequence of ations we then can have a clue of what kinda person he is.

In my opinion, “play a little trick(fun) at the first place“ doesn’t mean being dishonest. Whatever the reason is, it's nothing more than an action. See it as a tool, a knife in kitchen could be a handy utensils, while it could be deadly weapon in the hand of offenders.

I understand it’s a fairly personal thing, I’m also influenced by my culture and surrounding and experience, so then I have my personality and preference. So I would rather say, no correct answer in this case, just open talk.

it’s good to have different opinions, and knowing how we look things differently. : )

Thanks for the article. These phrases are helpful to sound more fluent and impress your native speaking friends. It's not about trying to hide your true level but I have experience that adding in natural phrases such as this really make your native speaking guest comfortable and it shows you have a good interest in learning their language and culture. when you nail an expression in the right situation your guest will feel really happy at your genuine attempt at learning Chinese. 

pinyin would be really helpful next time though.