OK, I admit it. I'm old. But in the home where I grew up, "politesse," (AKA graciousness, or old-fashioned good manners) was not an option. I was reminded, innumerable times, to say "Please" when asking for something at the dinner table, and to say "Thank you" when it was handed to me. I have taught (and modeled) this same behavior for my children.
"Politesse" was an incalculable benefit when I was able to take the trip of a lifetime several years ago, throughout Europe. I made sure I could say "please," and "thank you," at the very least, in the language of every country I visited. If I could say more in the language of the local country, I did so. I didn't worry about getting it right. My high school Spanish teacher had assured me years before that you got points just for trying. Getting it perfect was whipped cream on top.
Extending courtesy to random others is hardly something to be "discarded." You never know when the benefits will pay you back many-fold.