Pleasantaries

Interacting with people has become commonplace; you can't go an hour without exchanging pleasantries. Considering that these pleasantries have been around for so long, one would rightly assume that they have more purpose than simply being a mode to express politeness. Polite speech has developed to become a way to make people more receptive to what the speaker has to say. Polite speech has no intrinsic value, but the value of it comes from what the speaker would like to accomplish.

Take for example the setting of a school - it would be considered rude to not use polite speech when addressing a superior. Looking at the most common use of polite speech is simply how we address our teachers; we address them with prefixes that demonstrate respect such as "Mr." or "Ms." Without these titles, a teacher would simply scoff at whatever else one has to say. Not only are titles the only way to demonstrate respect, we often use the subjunctive as a way of demonstrating this respect. This is shown by phrases like "may I" or "can we". What this does is that it makes whoever we are talking to far more receptive to what we have to say. Without polite speech like that, the chances of a superior taking an following requests seriously sharply declines. 

Obviously, polite speech isn't just limited to our communication with superiors, we also use it when communicating to equals, such as friends. All people have needs and wants, and often, we are incapable of satisfying them by ourselves, hence we turn to other people. To make people more receptive to our demands, we have to show to them politeness and kindness in order to make them more receptive to our demands.

Finally, here's a meme to go with this: 

Employee (Black): Hello, how may I help you?

Karen (Gray): I need to speak to the manager immediately!

Employee (Black): What? No!

Here we can see how Karen's lack of politeness leads to her being unable to speak to the manager - poor Karen.