Using the word “you” can prompt action. Using the words “we” or “us” can prompt inaction or passivity.

I like how  Michelle Mazur worded it in her story at How to Kill A Persuasive Speech With One Tiny Word – Business 2 Community:

Mazur says that the the most important word in any presentation is “you” because it gets people to take action and responsibility for what you’re telling them to do.

It can also increase offenses and adds a sense of precocious demand to those who use it, but it can sure be effective!