"if you don't like America than go" where's the balance?

I think most of us have seen or heard someone complain about America and then someone else responds with "well then leave."

I understand that this is not a helpful thing to say, but I'm being honest, I have had this reaction before.

Now to be clear I'm talking people who say things like

"who the f*** what's to live in America?"

"This is the worst place to live in" etc...

I wanted opinions because I know I have some biasim in this. I spent 7 years of my childhood living in poverty stricken countries. (My mom taught ASL to deaf kids in 3rd world countries.) I've seen what I think is some of the worst modern day oppression. Also, I'm white so my USA experience has been pretty good. So yes, I definitely feel like when people complain about America they are incredibly clueless and would be thrown for a loop if they lived somewhere else.

HOWEVER, I also understand people saying "if you don't like America then just leave" can be a way to dismiss people who want to bring change and aren't afraid to talk about the issues in the USA. USA is far from perfect, that's for sure.

So what's the balance? Should people who live in America be more appreciative? Is saying "just leave" a valid thing to say in some cases?

EDIT****

Just want to add that I have NEVER told someone to leave America if they don't like it, but it has crossed my mind.