iCloud is a relatively small amount of storage. Even if you pay for more, don't you max out at 20GB? iCloud is all about having all of your information available on all of your devices without having to specifically sync each device. It's not really about replacing local storage of large files (which tend to be media and apps).
What about iTunes match? I don't use the service, so I'm not too clear on it. My understanding was that you didn't need your music locally to use that.