Haha I wonder that same thing sometimes!

I think you'll find though that a lot of the fundamental skills that the LSAT tests are actually pretty applicable to what will be required of you in law school: efficiently reading and comprehending dense/complex passages, recognizing the strength and nature of of language (the difference is words like "all" vs "most", for instance), making proper inferences and avoiding unknown assumptions, etc. And that should come as good news, since it means that as you get better at the LSAT you'll also be developing tools that will help you out down the road.
With the LSAT, the content of the questions and types of question asked are not designed to and do not test your knowledge of or proficiency with the law because you have not yet learned the fundamentals of the law by having gone to Law School. Rather, you are being screened as a candidate seeking to get educated about the law and being evaluated about whether or not you have
acquired the relevant and necessary intellectual and logical thinking skills to be able to succeed in Law School.
The LSAT is a test designed to measure a defined range and set of skills and abilities that are necessary to perform well in Law School: Excellent reading, comprehension, knowledge/understanding of and ability to apply valid reasoning well to new facts of varied subject matter in arguments and other types of materials from various angles. That's why the various different types of logical reasoning question types ask you to perform types of analysis of the material in the stimulus that are common types of analysis tasks lawyers must do.
These are all skills that are vital to being a successful Law Student and then a Lawyer. It also tests your ability to sort through distracter fluff information (in court cases and trials ever heard of the defense tactic "smoke and mirrors"), your ability to manage time wisely, your endurance and stamina (lawyers typically work many more than 8 hours a day) and many other important abilities.
I think it's a pretty well designed test for screening Law School hopefuls.