Why do you need parallel lines and perpendicular lines in your lives?
Construction, engineering, drawing, and architecture all use
parallel and perpendicular lines. Other than that, it is an
important topic because you are learning how to apply the language
and tools of mathematics to an intuitive system. These topics have
proven important in the history of human kind and also many before
you have shown that by learning about parallel and perpendicular
lines, one learns how to use math and logic. It is doubtful that
you can make a living off of parallel and perpendicular lines, but
if you can't understand parallel and perpendicular lines, then I
worry about your future.