Well maybe you think it's easier to just tell people what to do with authority, however on the initial front it's actually more work than its worth in the long run.
When you deny the other person that you're trying to direct any type of dialogue it robs them of their needs to feel validated and therefore they will contest regardless of how sound or logical your directive is, you must be open to dialogue.
It's important to realize that you're playing with people's emotions as well on top of telling people what you would like them to do.
If the person that you're throwing directives at does not mind being a submissive servant to your will then there is no problem. However I have yet to find someone who is willing to be that guy.
One of the most important things that you can do is give the person who you are talking to the opportunity to have a dialogue sometimes if not most times there's a reasoning to their logic as well.
In an employee's setting it is actually easier to ask somebody if they be willing to accomplish a task even though it is rightfully known that they are expected to accomplish the task the methodology of asking them simulates choice
If you have a proper hierarchy setup then the format choice would be automatically directed in the direction you needed to them to go.
if a manager asks an employee to clean the floor the employee knows that it is his job to do as the manager requests and therefore will most likely comply with the requirements.
However if you demand the employee clean the floor they will contest because they've been robbed of choice even if the choice is an illusion, it is still missing from the equation.
You will find that most humans want to succeed for their own self-worth and maybe the worth of others or a collective worth.
Most importantly when you deny someone a choice you will find yourself walking back your demand into a format of a question. it would have been easier to start off by asking a question in the first place even if the question is formatted to be a directive.