You are right, the majority of people will like the idea to get money for just posting around your favorite topic. But SteemIt is much more. Even though Steemit currently have only about 25000 active users daily, I can't find such a useful content on any other social network. Generally people work hard on their posts because any good piece of content here has a good chance to be seen by many smart people, get smart responses, as well as earning very solid income.
I really think SteemIt is just a brilliant project - it allow people to show their best.