This principle is called 'net neutrality': ISPs can't intentionally serve certain content faster or slower, or charge different rates for different content. And I'm fairly confident that 96%+ of internet users like it this way.
Think of a comparable example: cable television. Wouldn't it be great if you paid a single rate, and had access to all cable channels? If you didn't have to weigh different plans and packages from different providers to get all the channels you wanted to see? Well, the reason you can't do that is because there is no concept of 'net neutrality' which governs cable television.
So, if you're upset because you want to pay your ISP more money for worse internet service, and you hate the fact that you're able to access 100% of the content available on the internet, then the FCC's plan to eliminate net neutrality is for you.
But if you like, say, the fact that literally anyone, no matter how limited their means, can jump on the internet and post their opinion about matters profound and trivial, you should support net neutrality.
If you're a small business, and you like using the internet to promote your business, you should support it. If you like the fact that customers can navigate to your site as easily as they can navigate to Yahoo or Facebook or Twitter, you should support it.
If you're still not convinced, maybe this explainer from Save the Internet will be more persuasive than I am. Or maybe this description of the internet without net neutrality will be. Or maybe, you don't want the internet in the U.S. to look like it does in Portugal:
The FCC is voting on December 14 to permanently eliminate net neutrality. Doing so would be nothing more than a huge giveaway to big ISPs, which would be of no benefit whatsoever to average Americans or most businesses. Fortunately, Mashable is on the case, and lists a number of steps you can take in the next 3 weeks to try to block this action. Please read, take appropriate action, and urge others to do the same.