Imagine somebody is presenting you with a huge sum of information on how to do something, instructions on how to operate something, or even a lecture within a classroom. You only have mere seconds to take in and comprehend what's being said...and only one opportunity to do so. But either the speaker talks quickly or maybe you aren't listening. Thus, you fail to learn anything.
Now why would you want to be a better learner in the first place? The more you know, the more knowledgeable you become — and the more your vast intelligence and various skill sets will impress people. Knowledge is power, and the ultimate form of currency you can invest in yourself.
That's why you should want to improve your learning ability.