I wouldn't say Objective-C is supposed to be "a better
C", just different, and better. They're quite different (besides the obvious fact that Objective-C is indeed a superset of C). C is a statically typed procedural language while Objective-C is a very dynamic object oriented language with optional static typing.
It's really quite elegant if you think about it. It's a highly dynamic language that was designed more than 20 years ago and is still very relevant today as the platform of choice for developing nearly all Mac OS X and iPhone apps. As far as dynamic languages go it's very fast since it's compiled. It integrates seamlessly with C (and even C++).
Just because you don't know or care about Objective-C doesn't mean there aren't plenty of people who do. I regularly see articles about Objective-C on the front page of Hacker News, Reddit, etc.