527 committees are an important part of the american political system because they

are able to raise and spend unlimited amounts of money as long as they do not coordinate their activities with a political party.

Explanation:

Electoral processes are extremely expensive. It is almost impossible for an individual to promote him/herself to the public with personal wealth.

This is where 527 committees fit in the picture. The purpose of this committee is to 'influence' the result of the election.  They can technically openly aligned themselves with a single candidate, but they can help with the funding for a certain type of cause that might be carried by several candidates at once.