What is the purpose of studying counterpoint?

[Blanche_Minim]

I am currently studying counterpoint right now with my composition teacher. My question is why study counterpoint? I don't understand the purpose of it. How does it help you in your music as a composer? I also did advanced harmony and I also don't understand what's the point of it. I observe that four - part harmony is only used in an ending of a piece. My other question is that how is counterpoint relevant in today's contemporary music. Because in my counterpoint studies, I have to study Bach's fugues and that's classical music. I heard the Beatles used counterpoint in their music. Don't get me wrong, I love studying counterpoint and I will be learning 4:1 counterpoint, strict counterpoint, and free counterpoint. In counterpoint and harmony, I have to learn a lot of rules such as avoiding parallel movement and direct movement. And is it also possible that you use an existing melody such as your favorite song and use that melody as a bass line and make a counter - melody out of it? But can someone explain to me what's the purpose of studying counterpoint.

[Bellini48]

It is always an asset to know the rules as a pro, so that you can break them as a master. Counterpoint is something you can play with, even in more modern ways, in polyphony. Pentatonix does so. Eric Whitacre also. And they have broken 'likes' on youtube with their counterpointal daring. But to honestly abate those strict walls you need to know them well. Let me add some examples here for the listening.
http://www.youtube.com/watch?v=WSUFzC6_fp8
http://www.youtube.com/watch?v=V3rRaL-Czxw Notice Whitacre's 7 note cluster chord toward the middle of the piece...extraordinary. This amazong work is full of masterful dissonances. And he is a master of harmonization.
And this one: http://www.youtube.com/watch?v=nn5ken3RJBo
Harmony and counterpoint. Magistrally executed with the occasional dissonance and break of rules. But these are all well studied masters. Have patience and give it your best shot at the formality. Then BREAK IT ALL TO YOUR HEART'S CONTENT.