That doesn't mean shorter is always better. When you take away necessary detail to make things shorter, you wind up with a shorter, less perfect law.
For instance, if the law was "No driving over 70mph on I-75", shortening the law to "No driving" isn't an improvement. And even if we maintain the detail and shorten to "No 70+mph driving @ I-75" it doesn't improve things.
Concise is good. shortness for shortness sake is not. We don't need to be playing code golf with laws.