The Gift of Fight or Flight?

My brain is an interesting place for sure. I've been considering what it is to either react or respond and what within my brain chooses one or the other of those two choices. 

It was very enlightening when I first read somewhere that if I speak to another person such that I illicit a response the conversation will be different than if I speak in such a way that I illicit a reaction.

That knowledge right there gave me wonderful freedom in knowing how to effectively promote a useful conversation.

For example, someone could say to me; "Why did you plant that bizarre, twisty shaped

shrub in your garden?" Or they could say; "Hmm, that is certainly an interesting choice of bush to put in front of your house."

In my brain the first comment heads me right to a reaction. "What do you mean "bizarre?" Why are you picking on me? You obviously have bad taste if you don't see this choice of shrub as being a good choice." And on and on it would go. My ego is activated and I defend and react and attack in return.

With the second comment I am invited into a conversation. I don't have to tamp down and restrain my injured ego, I can just explain what and how I was thinking when I choose that shrub and that spot.

This has a lot to do with the human brain's gift of fight or flight. How do you think that is so? And why?