If the light bulb was the way the speaker is, and you couldn't focus or sharpen the edges or define it, we wouldn't have that, or movies in general, or computers, or T.V. sets, or C.D.s, or DVDs, and just go down the list of what the importance is of being able to focus light.
Si la bombilla fuera como es el altavoz, y no pudieramos dirigirla, ajustarla o definirla, no tendríamos esto, o películas en general, u ordenadores, o televisores. o CDs, o DVDs, y así sigue la lista de lo importante que es ser capaz de dirigir la luz.